None this week (other than this blog post).
Answers to Last Week’s Question
If you want to check your answer from last week:
Well, I must confess I don’t know for sure if this is the right answer or not. In theory I could write a program to do a brute-force solution with all twelve towers – if each tower is either Swarm, Boost or Nothing (simply don’t build a tower in that location), then it’s “only” 3^12 possibilities – but I don’t have the time to do that at this moment. If someone finds a better solution, feel free to post here!
By playing around by hand in a spreadsheet, the best I came up with was the top and bottom rows both consisting of four Swarm towers, with the center row holding four Boost towers, giving a damage/cost ratio of 1.21.
The two Boost towers in the center give +50% damage to six Swarm towers surrounding them, thus providing a damage bonus of 1440 damage each, while the two Boost towers on the side support four Swarm towers for a damage bonus of 960 each. On average, then, Boost towers provide 1200 damage for a cost of 500, or a damage/cost ratio of 2.4.
Each Swarm tower provides 480 damage (x8 = 3840 damage, total). Each tower costs 640, for a damage/cost ratio of 0.75 for each one. While this is much less efficient than the Boost towers, the Swarm towers are still worth having; deleting any of them makes the surrounding Boost towers less effective, so in combination the Swarm towers are still more cost-efficient than having nothing at all.
However, the Boost towers are still much more cost-effective than Swarm towers (and if you look at the other tower types, Boost towers are the most cost-effective tower in the game, hands-down, when you assume many fully-upgraded towers surrounding them). The only thing that prevents Boost towers from being the dominant strategy at the top levels of play, I think, is that you don’t have enough cash to make full use of them. A typical game that lasts 40 levels might only give you a few thousand dollars or so, which is just not enough to build a killer array of fully-upgraded towers. Or, maybe there’s an opportunity for you to find new dominant strategies that have so far gone undiscovered…
In the syllabus, this week is listed as “advancement, progression and pacing for single-player games” but I’ve changed my mind. A lot of games feature some kind of advancement and pacing, even multiplayer games. There’s the multiplayer co-op games, like the tabletop RPG Dungeons & Dragons or the console action-RPG Baldur’s Gate: Dark Alliance or the PC game Left 4 Dead. Even within multiplayer competitive games, some of them have the players progressing and getting more powerful during play: players get more lands and cast more powerful spells as a game of Magic: the Gathering progresses, while players field more powerful units in the late game of Starcraft. Then there are MMOs like World of Warcraft that clearly have progression built in as a core mechanic of the game, even on PvP servers. So in addition to single-player experiences like your typical Final Fantasy game, we’ll be talking about these other things too: basically, how do you balance progression mechanics?
Wait, What’s Balance Again?
First, it’s worth a reminder of what “balance” even means in this context. As I said in the intro to this course, in terms of progression, there are three things to consider:
- Is the difficulty level appropriate for the audience, or is the game overall too hard or too easy?
- As the player progresses through the game, we expect the game to get harder to compensate for the player’s increasing skill level because they are getting better; does the difficulty increase at a good rate, or does it get too hard too fast (which leads to frustration), or does it get harder too slowly (leading to boredom while the player waits for the game to get challenging again)?
- If your avatar increases in power, whether that be from finding new game objects like better weapons or tools or other toys, gaining new special abilities, or just getting a raw boost in stats like Hit Points or Damage, are you gaining these at a good rate relative to the increase in enemy power? Or do you gain too much power too fast (making the rest of the game trivial after a certain point), or do you gain power too slowly (requiring a lot of mindless grinding to compensate, which artificially lengthens the game at the cost of forcing the player to re-play content that they’ve already mastered)?
We will consider each of these in turn.
If you’re not familiar with the concept of “flow” then read up here from last summer’s course. Basically, this says that if the game is too hard for your level of skill you get frustrated, if it’s too easy you get bored, but if you’re challenged at the peak of your ability then you find the game engaging and usually more fun, and one of our goals as game designers is to provide a suitable level of challenge to our players.
There’s two problems here. First, not every player comes to the game with the same skill level, so what’s too easy for some players is too hard for others. How do you give all players the same experience but have it be balanced for all of them?
Second, as a player progresses through the game, they get better at it, so even if the game’s challenge level remains constant it will actually get easier for the player.
How do we solve these problems? Well, that’s most of what this week is about.
Why Progression Mechanics?
Before moving on, though, it’s worth asking what the purpose is behind progression mechanics to begin with. If we’re going to dedicate a full tenth of this course to progression through a game, progression mechanics should be a useful design tool that’s worth talking about. What is it useful for?
Ending the game
In most cases, the purpose of progression is to bring the game to an end. For shorter games especially, the idea is that progression makes sure the game ends in a reasonable time frame. So whether you’re making a game that’s meant to last 3 minutes (like an early-80s arcade game) or 30-60 minutes (like a family board game) or 3 to 6 hours (like a strategic wargame) or 30 to 300 hours (like a console RPG), the idea is that some games have a desired game length, and if you know what that length is, forced progression keeps it moving along to guarantee that the game will actually end within the desired time range. We’ll talk more about optimal game length later in this post.
Reward and training for the elder game
In a few specialized cases, the game has no end (MMOs, Sims, tabletop RPGs, or progression-based Facebook games), so progression is used as a reward structure and a training simulator in the early game rather than a way to end the game. This has an obvious problem which can be seen with just about all of these games: at some point, more progression just isn’t meaningful. The player has seen all the content in the game that they need to, they’ve reached the level cap, they’ve unlocked all of their special abilities in their skill tree, they’ve maxed their stats, or whatever. In just about all cases, when the player reaches this point, they have to find something else to do, and there is a sharp transition into what’s sometimes called the “elder game” where the objective changes from progression to something else. For players who are used to progression as a goal, since that’s what the game has been training them for, this transition can be jarring. The people who enjoy the early-game progression may not enjoy the elder game activities as much since they’re so different (and likewise, some people who would love the elder game never reach it because they don’t have the patience to go through the progression treadmill).
What happens in the elder game?
In Sim games and FarmVille, the elder game is artistic expression: making your farm pretty or interesting for your friends to look at, or setting up custom stories or skits with your sims.
In MMOs, the elder game is high-level raids that require careful coordination between a large group, or PvP areas where you’re fighting against other human players one-on-one or in teams, or exploring social aspects of the game like taking on a coordination or leadership role within a Guild.
In tabletop RPGs, the elder game is usually finding an elegant way to retire your characters and end the story in a way that’s sufficiently satisfying, which is interesting because in these games the “elder game” is actually a quest to end the game!
What happens with games that end?
In games where progression does end the game, there is also a problem: generally, if you’re gaining power throughout the game and this serves as a reward to the player, the game ends right when you’re reaching the peak of your power. This means you don’t really get to enjoy being on top of the world for very long. If you’re losing power throughout the game, which can happen in games like Chess, then at the end you just feel like you’ve been ground into the dirt for the entire experience, which isn’t much better.
Peter Molyneux has pointed out this flaw when talking about the upcoming Fable 3, where he insists you’ll reach the peak of your power early on, succeed in ruling the world, and then have to spend the rest of the game making good on the promises you made to get there… which is a great tagline, but really all he’s saying is that he’s taking the standard Console RPG progression model, shortening it, and adding an elder game, which means that Fable 3 will either live or die on its ability to deliver a solid elder-game experience that still appeals to the same kinds of players who enjoyed reaching that point in the first place. Now, I’m not saying it can’t be done, but he’s got his work cut out for him. In the interview I saw, it sounded like he was treating this like a simple fix to an age-old problem, but as we can see here it’s really just replacing one difficult design problem with another. I look forward to seeing if he solves it… because if he does, that will have major applications for MMOs and FarmVille and everything with an elder game in between.
Two Types of Progression
Progression tends to work differently in PvP games compared to PvE games. In PvP (this includes multi-player PvP like “deathmatch” and also single-player games played against AI opponents), you’re trying to win against another player, human or AI, so the meaning of your progression is relative to the progression of your opponents. In PvE games (this includes both single-player games and multi-player co-op) you are progressing through the game to try to overcome a challenge and reach some kind of end state, so for most of these games your progress is seen in absolute terms. So that is really the core distinction I’d like to make, games where the focus is either on relative power between parties, or absolute power with respect to the game’s core systems. I’m just using “PvP” and “PvE” as shorthand here, and if I slip up and refer to PvP as “multi-player” and PvE as “single-player” that is just because those are the most common design patterns.
Challenge Levels in PvE
When you’re progressing through a bunch of challenges within a game, how do you track the level of challenge that the player is feeling, so you know if it’s increasing too quickly or too slowly, and whether the total challenge level is just right?
This is actually a tricky question to answer, because the “difficulty” felt by the player is not made up of just one thing here, it’s actually a combination of four things, but the player experiences it only as a single “am I being challenged?” feeling. If we’re trying to measure the player perception of how challenged they are, it’s like if the dashboard of your car took the gas, current speed, and engine RPMs and multiplied them all together to get a single “happiness” rating, and you only had this one number to look at to try to figure out what was causing it to go up or down.
The four components of perceived difficulty
First of all, there’s the level of the player’s skill at the game. The more skilled the player is at the game, the easier the challenges will seem, regardless of anything else.
Second, there’s the player’s power level in the game. Even if the player isn’t very good at the game, doubling their Hit Points will still keep them alive longer, increasing their Attack stat will let them kill things more effectively, giving them a Hook Shot lets them reach new places they couldn’t before, and so on.
Third and fourth, there’s the flip side of both of these, which are how the game creates challenges for the player. The game can create skill-based challenges which require the player to gain a greater amount of skill in the game, for example by introducing new enemies with better AI that make them harder to hit. Or it can provide power-based challenges, by increasing the hit points or attack power or other stats of the enemies in the game (or just adding more enemies in an area) without actually making the enemies any more skilled.
Skill and power are interchangeable
You can substitute skill and power, to an extent, either on the player side or the challenge side. We do this all the time on the challenge side, adding extra hit points or resource generation or otherwise just using the same AI but inflating the numbers, and expecting that the player will need to either get better stats themselves or show a higher level of skill in order to compensate. Or a player who finds a game too easy can challenge themselves by not finding all of the power-ups in a game, giving themselves less power and relying on their high level of skill to make up for it (I’m sure at least some of you have tried beating the original Zelda with just the wooden sword, to see if it could be done). Creating a stronger AI to challenge the player is a lot harder and more expensive, so very few games do that (although the results tend to be spectacular when they do – I’m thinking of Gunstar Heroes as the prototypical example).
At any rate, we can think of the challenge level as the sum of the player’s skill and power, subtracted from the game’s skill challenges and power challenges. This difference gives us the player’s perceived level of difficulty. So, when any one of these things changes, the player will feel the game get harder or easier. Written mathematically, we have this equation:
PerceivedDifficulty = (SkillChallenge + PowerChallenge) – (PlayerSkill + PlayerPower)
Example: perceived challenge decreases naturally
How do we use this information? Let’s take the player’s skill, which generally increases over time. That’s significant, because it means that if everything else is equal, that is if the player’s power level, and the overall challenge in the game stay the same, over time the player will feel like the game is getting easier, and eventually it’ll be too easy. To keep the player’s attention once they get better, every game must get harder in some way. (Or at least, every game where the player’s skill can increase. There are some games with no skill component at all, and those are exempted here.)
Changing player skill
Now, you might think the player skill curve is not under our control. After all, players come to our game with different pre-existing skill levels, and they learn at different rates. However, as designers we actually do have some control over this, based on our mechanics:
- If we design deep mechanics that interact in a lot of ways with multiple layers of strategy, so that mastering the basic game just opens up new ways to look at the game at a more abstract meta-level, the player’s skill curve will be increasing for a long time, probably with certain well-defined jumps when the player finally masters some new way of thinking, like when a Chess player first starts to learn book openings, or when they start understanding the tradeoffs of tempo versus board control versus total pieces on the board.
- If our game is more shallow, or has a large luck component, we will expect to see a short increase in skill as the player masters what little they can, and then a skill plateau. There are plenty of valid design reasons to do this intentionally. One common example is educational games, where part of the core vision is that you want the player to learn a new skill from the game, and then you want them to stop playing so they can go on to learn other things. Or this might simply be the tradeoff for making your game accessible: “A minute to learn, a minute to master.”
- You can also control how quickly the player learns, based on the number of tutorials and practice areas you provide. One common design pattern, popularized by Valve, is to give the player some new weapon or tool or toy in a safe area where they can just play around with it, then introduce them immediately to a relatively easy area where they are given a series of simple challenges that let them use their new toy and learn all the cool things it can do, and then you give them a harder challenge where they have to integrate the new toy into their existing play style and combine it with other toys. By designing your levels to teach the player specific skills in certain areas, you can ramp the player up more quickly so they can increase their skill faster.
- What if you don’t want the player to increase in skill quickly, because you want the game to last longer? If you want the player to learn more slowly, you can instead use “skill gating” as I’ve heard it called. That is, you don’t necessarily teach the player how to play your game, or hold their hand through it. Instead, you simply offer a set of progressively harder challenges, so you are at least guaranteed that if a player completes one challenge, they are ready for the next: each challenge is essentially a signpost that says “you must be at least THIS GOOD to pass.”
Measuring the components of perceived challenge
Player skill is hard to measure mathematically on its own, because as I said earlier, it is combined with player power in any game that includes both. For now, I can say that the best way to get a handle on this is to use playtesting and metrics, for example looking at how often players die or are otherwise set back, where these failures happen, how long it takes players to get through a level the first time they encounter it, and so on. We’ll talk more about this next week.
Player power and power-based challenges are much easier to balance mathematically: just compare the player power curve with the game’s opposition power curve. You have complete control over both of these; you control when the player is gaining power, and also when their enemies are presenting a larger amount of power to counter them. What do you want these curves to look like? Part of it depends on what you expect the skill curve to be, since you can use power as a compensatory mechanism in either direction. As a general guideline, the most common pattern I’ve seen looks something like this: within a single area like an individual dungeon or level, you start with a sudden jump in difficulty since the player is entering a new space after mastering the old one. Over time, the player’s power increases, either through level-ups or item drops, until they reach the end of the level where there may be another sudden difficulty jump in the form of a boss, and then after that typically another sudden jump in player power when they get loot from the boss or reach a new area that lets them upgrade their character.
Some dungeons split themselves into several parts, with an easier part at the beginning, then a mid-boss, then a harder part, and then a final boss, but really you can just think of this as the same pattern repeated several times without a change of graphical scenery. String a bunch of these together and that’s the power progression in your game: the difficulty jumps initially in a new area, stays constant awhile, has a sudden jump at the end for the boss, then returns; meanwhile the player’s power has sudden jumps at the end of an area, with incremental gains along the way as they find new stuff or level up.
That said, this is not the only pattern of power progression, not even necessarily the best for your game! These will vary based on genre and intended audience. For Space Invaders, over the course of a single game, the game’s power challenges, player skill and player power are all constant; the only thing that increases is the game’s skill challenge (making the aliens start faster and lower to the ground in each successive wave) until eventually they present a hard enough challenge to overwhelm the player.
Rewards in PvE
In PvE games especially, progression is strongly related to what is sometimes called the “reward schedule” or “risk/reward cycle.” The idea is that you don’t just want the player to progress, you want them to feel like they are being rewarded for playing well. In a sense, you can think of progression as a reward itself: as the player continues in the game and demonstrates mastery, the ability to progress through the game shows the player they are doing well and reinforces that they’re a good player. One corollary here is that you do need to make sure the player notices you’re rewarding them (in practice, this is usually not much of a problem). Another corollary is that timing is important when handing out rewards:
- Giving too few rewards, or spacing them out for too long so that the player goes for long stretches without feeling any sense of progression, is usually a bad thing. The player is demoralized and may start to feel like if they aren’t making progress, they’re playing the game wrong (even if they’re really doing fine).
- Ironically, giving too many rewards can also be hazardous. One of the things we’ve learned from psychology is that happiness comes from experiencing some kind of gain or improvement, so many little gains produce a lot more happiness than one big gain, even if they add up to the same thing. Giving too many big rewards in a small space of time diminishes their impact.
- Another thing we know from psychology is that a random reward schedule is more powerful than a fixed schedule. This does not mean that the rewards themselves should be arbitrary; they should be linked to the player’s progress through the game, and they should happen as a direct result of what the player did, so that the player feels a sense of accomplishment. It is far more powerful to reward the player because of their deliberate action in the game, than to reward them for something they didn’t know about and weren’t even trying for.
I’ll give a few examples:
- Have you ever started a new game on Facebook and been immediately given some kind of trophy or “achievement unlocked” bonus just for logging in the first time? I think this is a mistake a lot of Facebook games make: they give a reward that seems arbitrary, and it actually waters down the player’s actual achievements later. It gives the impression that the game is too easy. Now, for some games, you may want them to seem easy if they are aimed at an extremely casual audience, but the danger is reducing the actual, genuine feelings of accomplishment the player gets later.
- “Hidden achievements” in Xbox 360 games, or their equivalents on other platforms. If achievements are a reward for skill, how is the player to know what the achievement is if it’s hidden? Even more obnoxious, a lot of these achievements are for things that aren’t really under player control and that seem kind of arbitrary, like “do exactly 123 damage in a single attack” where damage is computed randomly. What exactly is the player supposed to feel rewarded for here?
- A positive example would be random loot drops in a typical action game or action-RPG. While these are random, and occasionally the player gets a really cool item, this is still tied to the deliberate player action of defeating enemies, so the player is rewarded but on a random schedule. (Note that you can play around with “randomness” here, for example by having your game track the time between rare loot drops, and having it deliberately give a big reward if the player hasn’t seen one in awhile. Some games split the difference, with random drops and also fixed drops from specific quests/bosses, so that the player is at least getting some great items every now and then.)
- Another common example: the player is treated to a cut-scene once they reach a certain point in a dungeon. Now, at first you might say this isn’t random – it happens at exactly the same point in the game, every time, because the level designer scripted that event to happen at exactly that place! And on multiple playthroughs you’d be correct… but the first time a player experiences the game, they don’t know where these rewards are, so from the player’s perspective it is not something that can be predicted; it may as well be random.
Now I’d like to talk about three kinds of rewards that all relate to progression: increasing player power, level transitions, and story progression.
Rewarding the player with increased power
Progression through getting a new toy/object/capability that actually increases player options is another special milestone. Like we said before, you want these spaced out, though a lot of times I see the player get all the cool toys in the first third or half of the game and then spend the rest of the game finding new and interesting ways to use them. This can be perfectly valid design; if the most fun toy in your game is only discovered 2/3rds of the way through, that’s a lot of time the player doesn’t get to have fun – Valve made this example famous through the Gravity Gun in Half-Life 2: as the story goes, they initially had you get this gun near the end of the game, but players had so much fun with it that they restructured their levels to give it to the player much earlier. Still, if you give the player access to everything early on, you need to use other kinds of rewards to keep them engaged through the longer final parts of the game where they don’t find any new toys. How can you do this? Here’s a few ways:
- If your mechanics have a lot of depth, you can just present unique combinations of things to the player to keep them challenged and engaged. (This is really hard to do in practice.)
- Use other rewards more liberally after you shut off the new toys: more story, more stat increases, more frequent boss fights or level transitions. You can also offer upgrades to their toys, although it’s debatable whether you can think of an “upgrade” as just another way of saying “new toy.”
- Or you can, you know, make your game shorter. In this day and age, thankfully, there’s no shame in this. Portal and Braid are both well-known for two things: being really great games, and being short. At the big-budget AAA level, Batman: Arkham Asylum was one of the best games of last year (both in critical reception and sales), even though I hear it only lasts about ten hours or so.
Rewarding the player with level transitions
Progression through level transitions – that is, progression to a new area – is a special kind of reward, because it makes the player feel like they’re moving ahead (and they are!). You want these spaced out a bit so the player isn’t so overwhelmed by changes that they feel like the whole game is always moving ahead without them; a rule of thumb is to offer new levels or areas on a slightly increasing curve, where each level takes a little bit longer than the last. This makes the player feel like they are moving ahead more rapidly at the start of the game when they haven’t become as emotionally invested in the outcome; a player can tolerate slightly longer stretches between transitions near the end of the game, especially if they are being led up to a huge plot point. Strangely, a lot of this can be done with just the visual design of the level, which is admittedly crossing from game design into the territory of game art: for example, if you have a really long dungeon the players are traversing, you can add things to make it feel like each region of the dungeon is different, maybe having the color or texture of the walls change as the player gets deeper inside, to give the player a sense that they are moving forward.
Rewarding the player with story progression
Progression through plot advancement is interesting to analyze, because in so many ways the story is separate from the gameplay: in most games, knowing the characters’ motivations or their feelings towards each other has absolutely no meaning when you’re dealing with things like combat mechanics. And yet, in many games (originally this was restricted to RPGs, but we’re seeing story integrated into all kinds of games these days), story progression is one of the rewards built into the reward cycle.
Additionally, the story itself has a “difficulty” of sorts (we call it “dramatic tension”), so another thing to consider in story-based games is whether the dramatic tension of the story overlaps well with the overall difficulty of the game. Many games do not: the story climax is at the end, but the hardest part of the game is in the middle somewhere, before you find an uber-powerful weapon that makes the rest of the game easy. In general, you want rising tension in your story while the difficulty curve is increasing, dramatic climaxes (climaxen? climaces?) at the hardest part, and so on; this makes the story feel more integrated with the mechanics, all thanks to game balance and math. It’s really strange to write that you get a better story by using math, but there you are. (I guess another way of doing this would be to force the story writers to put their drama in other places to match the game’s difficulty curve, but in practice I think it’s easier to change a few numbers than to change the story.)
Combining the types of rewards into a single reward schedule
Note that a reward is a reward, so you don’t just want to space each category of rewards out individually, but also interleave them. In other words, you don’t need to have too many overlaps, where you have a level transition, plot advancement, and a power level increase all at once.
Level transitions are fixed, so you tend to see the power rewards sprinkled throughout the levels as rewards between transitions. Strangely, in practice, a lot of plot advancement tends to happen at the same time as level transitions, which might be a missed opportunity. Some games take the chance to add some backstory in the middle of levels, in areas that are otherwise uninteresting… although then the danger is that the player is getting a reward arbitrarily when they feel like they weren’t doing anything except walking around and exploring. A common design pattern I see in this case is to split the difference by scripting the plot advancement so it immediately follows a fight of some kind. Even if it’s a relatively easy fight, if it’s one that’s scripted, the reward of revealing some additional story immediately after can make the player feel like they earned it.
Challenge Levels in PvP
If PvE games are all about progression and rewards, PvP games are about gains and losses relative to your opponents. Either directly or indirectly, the goal is to gain enough power to win the game, and there is some kind of tug-of-war between the players as each is trying to get there first. I’ll remind you that when I’m saying “power” in the context of progression, I’m talking about the sum of all aspects of the player’s position in the game, so this includes having more pieces and cards put into play, more resources, better board position, taking more turns or actions, or really anything that affects the player’s standing (other than the player’s skill level at playing the game). The victory condition for the game is sometimes to reach a certain level of power directly; sometimes it is indirect, where the actual condition is something abstract like Victory Points, and it is the player’s power in the game that merely enables them to score those Victory Points. And in some cases the players don’t gain power, they lose power, and the object of the game is to get the opponent(s) to run out first. In any case, gaining power relative to your opponents is usually an important player goal.
Tracking player power as the game progresses (that is, seeing how power changes over time in a real-time game, or how it changes each turn in a turn-based game) can follow a lot of different patterns in PvP games. In PvE you almost always see an increase in absolute player power level over time (even if their power level relative to the challenges around them may increase or decrease, depending on the game). In PvP there are more options to play with, since everything is relative to the opponents and not compared with some absolute “you must be THIS GOOD to win the game” yardstick.
Positive-sum, negative-sum, and zero-sum games
This seems as good a time as any to talk about an important distinction in power-based progression that we borrow from the field of Game Theory: whether the game is zero-sum, positive-sum, or negative-sum. If you haven’t heard these terms before:
- Positive-sum means that the overall power in the game increases over time. Settlers of Catan is an example of a positive-sum game: with each roll of the dice, resources are generated for the players, and all players can gain power simultaneously without any of their opponents losing power. Monopoly is another example of a positive-sum game, because on average every trip around the board will give the player $200 (and that money comes from the bank, not from other players). While there are a few spaces that remove wealth from the game and are therefore negative-sum (Income Tax, Luxury Tax, a few of the Chance and Community Chest cards, unmortgaging properties, and sometimes Jail), on average these losses add up to less than $200, so on average more wealth is created than removed over time. Some players use house rules that give jackpots on Free Parking or landing exactly on Go, which make the game even more positive-sum. While you can lose lots of money to other players by landing on their properties, that activity itself is zero-sum (one player is losing money, another player is gaining the exact same amount). This helps explain why Monopoly feels to most people like it takes forever: it’s a positive-sum game so the average wealth of players is increasing over time, but the object of the game is to bankrupt your opponents which can only be done through zero-sum methods. And the house rules most people play with just increase the positive-sum nature of the game, making the problem worse!
- Zero-sum means that the sum of all power in the game is a constant, and can neither be created nor destroyed by players. In other words, the only way for me to gain power is to take it from another player, and I gain exactly as much as they lose. Poker is an example of a zero-sum game, because the only way to win money is to take it from other players, and you win exactly as much as the total that everyone else loses. (If you play in a casino or online where the House takes a percentage of each pot, it actually becomes a negative-sum game for the players.)
- Negative-sum means that over time, players actually lose more power than they gain; player actions remove power from the game without replacing it. Chess is a good example of a negative-sum game; generally over time, your force is getting smaller. Capturing your opponent’s pieces does not give those pieces to you, it removes them from the board. Chess has no zero-sum elements, where capturing an enemy piece gives that piece to you (although the related game Shogi does work this way, and has extremely different play dynamics as a result). Chess does have one positive-sum element, pawn promotion, but that generally happens rarely and only in the end game, and serves the important purpose of adding a positive feedback loop to bring the game to a close… something I’ll talk about in just a second.
An interesting property here is that changes in player power, whether zero-sum, positive-sum, or negative-sum, are the primary rewards in a PvP game. The player feels rewarded because they have gained power relative to their opponents, so they feel like they have a better chance of winning after making a particularly good move.
Positive and negative feedback loops
Another thing I should mention here is how positive and negative feedback loops fit in with this, because you can have either kind of feedback loop with a zero-sum, positive-sum or negative-sum game, but they work differently. In case you’re not familiar with these terms, “positive feedback loop” means that receiving a power reward makes it more likely that you’ll receive more, in other words it rewards you for doing well and punishes you for doing poorly; “negative feedback loop” is the opposite, where receiving a power reward makes it less likely you’ll receive more, so it punishes you for doing well and rewards you for doing poorly. I went into a fair amount of detail about these in last summer’s course, so I won’t repeat that here.
One interesting property of feedback loops is how they affect the player’s power curve. With negative feedback, the power curve of one player usually depends on their opponent’s power: they will increase more when behind, and decrease more when ahead, so a single player’s power curve can look very different depending on how they’re doing relative to their opponents, and this will look different from game to game.
With positive feedback, you tend to have a curve that gets more sharply increasing or decreasing over time, with larger swings in the endgame; unlike negative feedback, a positive feedback curve doesn’t always take the opponent’s standings into account… it can just reward a player’s absolute power.
Now, these aren’t hard-and-fast rules… a negative feedback loop can be absolute, which basically forces everyone to slow down around the time they reach the end game; and a positive feedback loop can be relative, where you gain power when you’re in the lead. However, if we understand the game design purpose that is served by feedback loops, we’ll see why positive feedback is usually independent of the opponents, while negative feedback is usually dependent.
The purpose of feedback loops in game design
The primary purpose of positive feedback is to get the game to end quickly. Once a winner has been decided and a player is too far ahead, you don’t want to drag it out because that wastes everyone’s time. Because of this, you want all players on an accelerating curve in the end game. It doesn’t really matter who is ahead; the purpose is to get the game to end, and as long as everyone gets more power, it will end faster.
By contrast, the primary purpose of negative feedback is to let players who are behind catch up, so that no one ever feels like they are in a position where they can’t possibly win. If everyone is slowed down in exactly the same fashion in the endgame, that doesn’t fulfill this purpose; someone who was behind at the beginning can still be behind at the end, and even though the gap appears to close, they are slowed down as much as anyone else. In order to truly allow those who are behind to catch up, the game has to be able to tell the difference between someone who is behind and someone who is ahead.
So, what does a player’s power curve look like in a PvP game? Here are a few ways you might see a player’s power gain (or loss) over time:
- In a typical positive-sum game, each player is gaining power over time in some way. That might be on an increasing, linear, or decreasing curve.
- In a positive-sum game with positive feedback, the players are gaining power over time and the more power they gain, the more they have, so it’s an increasing curve (such as a triangular or exponential gain in power over time) for each player. If you subtract one player’s curve from another (which shows you who is ahead, who is behind, and how often the lead is changing), usually what happens is one player gets an early lead and then keeps riding the curve to victory, unless they make a mistake along the way. Such a game is usually not that interesting for the players who are not in the lead.
- In a positive-sum game with negative feedback, the players are still on an increasing curve, but that curve is altered by the position of the other players, reducing the gains for the leader and increasing them further for whoever’s behind, so if you look at all the players’ power curves simultaneously you’ll see a sort of tangled braid where the players are constantly overtaking one another. Subtracting one player’s power from another over time, you’ll see that the players’ relative power swings back and forth, which is pretty much how any negative feedback should work.
- In a typical zero-sum game, players take power from each other, and the sum of all player power is a constant. In a two-player game, that means you could derive either player’s power curve just by looking at the other one.
- In a zero-sum game with positive feedback, the game may end quickly as one player takes an early advantage and presses it to gain even more of an advantage, taking all of the power from their opponents quickly. Usually games that fall into this category also have some kind of early-game negative feedback built in to prevent the game from coming to an end too early, unless the game is very short.
- In a zero-sum game with negative feedback, we tend to see swings of power that pull the leader back to the center. This keeps the players close, but also makes it very hard for a single player to actually win; if the negative feedback is too strong, you can easily end in a stalemate where neither player can win, which tends to be unsatisfying. A typical design pattern for zero-sum games in particular is to have some strong negative feedback mechanisms in the early game that taper off towards the end, while positive feedback increases towards the end of the game. This can end up as a pretty exciting game of back-and-forth where each player spends some time in the lead before one final, spectacular, irreversible triumph that brings the game to a close.
- In a typical negative-sum game, the idea is generally not for a player to acquire enough power to win, but rather for a player to lose the least power relative to their opponents. In negative-sum games, players are usually eliminated when they lose most or all of their power, and the object is either to be the last one eliminated, or to be in the best standing when the first opponent is eliminated. A player’s power curve might be increasing, decreasing or constant, sort of an inverse of the positive-sum game, and pretty much everything else looks like a positive-sum game turned upside down.
- In a negative-sum game with positive feedback, players who are losing will lose even faster. The more power a player has left over, the slower they’ll tend to lose it, but once they start that slide into oblivion it happens more and more rapidly.
- In a negative-sum game with negative feedback, players who are losing will lose slower, and players who have more power tend to lose it faster, so again you’ll see this “braid” shape where the players will chase each other downward until they start crashing.
Applied power curves
Now, maybe you can visualize what a power curve looks like in theory, showing how a player’s power goes up or down over time… but how do you actually make one for a real game?
The easiest way to construct a power curve is through playtest data. The raw numbers can easily allow you to chart something like this. The hardest part is coming up with some kind of numeric formula for “power” in the game: how well a player is actually doing in absolute terms. This is easier with some games than others. In a miniatures game like HeroClix or Warhammer 40K, each figurine you control is worth a certain number of points, so it is not hard to add your points together on any given turn to get at least a rough idea of where each player stands. In a real-time strategy game like Starcraft, adding a player’s current resources along with the resource costs of all of their units and structures would also give a reasonable approximation of their power over time. For a game like Chess where you have to balance a player’s remaining pieces, board position and tempo, this is a bit trickier. But once you have a “power formula” you can simply track it for all players over time through repeated playtests to see what kinds of patterns emerge.
Ending the game
One of the really important things to notice as you do this is the amount of time it takes to reach a certain point. You want to scale the game so that it ends in about as much time as you want it to.
The most obvious way to do that is by hard-limiting time or turns which guarantees a specific game length (“this game ends after 4 turns”); sometimes this is necessary and even compelling, but a lot of times it’s just a lazy design solution that says “we didn’t playtest this enough to know how long the game would take if you actually played to a satisfying conclusion.”
An alternative is to balance your progression mechanics to cause the game to end within your desired range. You can do this by changing the nature of how positive or negative sum your game is (that is, the base rate of combined player power gain or loss), or by adding, removing, strengthening or weakening your feedback loops. This part is pretty straightforward, if you collect all of the numbers that you need to analyze it. For example, if you take an existing positive feedback loop and make the effect stronger, the game will probably end earlier, so that is one way to shorten the game.
I should note that some PvP games have well-defined transitions between different game phases. The most common pattern here is a three-phase structure where you have an early game, a mid-game and an endgame, as made famous by Chess –which has many entire books devoted to just a single phase of the game. If you become aware of these transitions (or if you design them into the game explicitly), you don’t just want to pay attention to the player power curve throughout the game, but also how it changes in each phase, and the relative length of each phase.
For example, a common finding in game prototypes is that the endgame isn’t very interesting and is mostly a matter of just going through the motions to reach the conclusion that you already arrived at in mid-game. To fix this, you might think of adding new mechanics that come into play in the endgame to make it more interesting. Or, you might try to find ways to either extend the mid-game or shorten the endgame by adjusting your feedback loops and the positive, negative or zero-sum nature of your game during different phases.
Another common game design problem is a game that’s great once the players ramp up in mid-game, but the early game feels like it starts too slowly. One way to fix this is to add a temporary positive-sum nature to the early game in order to get the players gaining power and into the mid-game quickly.
In some games, the game is explicitly broken into phases as part of the core design. One example is the board game Shear Panic, where the scoring track is divided into four regions, and each region changes the rules for scoring which gives the game a very different feel in each of the game’s four phases. In this game, you transition between phases based on the number of turns taken in the game, so the length of each phase is dependent on how many turns each player has had. In a game like this, you could easily change the length of time spent in each phase by just increasing the length of that phase, so it lasts more turns.
Other games have less sharp transitions between different phases, and those may not be immediately obvious or explicitly designed. Chess is one example I’ve already mentioned. Another is Netrunner, an asymmetric CCG where one player (the Corporation) is trying to put cards in play and then spend actions to score the points on those cards, and the other player (the Runner) is trying to steal the points before they’re scored. After the game had been released, players at the tournament level realized that most games followed three distinct phases: the early game when the Runner is relatively safe from harm and could try to steal as much as possible; then the mid-game when the Corporation sets up its defenses and makes it prohibitively expensive, temporarily for the Runner to steal anything; and finally the endgame where the Runner puts together enough resources to break through the Corporation’s defenses to steal the remaining points needed for the win. Looked at in this way, the Corporation is trying to enter the second phase as early in the game as possible and is trying to stretch it out for as long as possible, while the Runner is trying to stay in the first phase as long as it can and then if it doesn’t win early, the Runner tries to transition from the second phase into the endgame before the Corporation has scored enough to win.
How do you balance the progression mechanics in something like this? One thing you can do, as was done with Netrunner, is to put the progression of the game under partial control of the players, so that it is the players collectively trying to push the game forward or hold it back. That creates an interesting meta-level of strategic tension.
Another thing you can do is include some mechanics that actually have some method of detecting what phase you’re in, or at the very least, that tend to work a lot better in some phases than others. Netrunner does this as well; for example, the Runner has some really expensive attack cards that aren’t so useful early on when they don’t have a lot of resources, but that help it greatly to end the game in the final phase. In this way, as players use new strategies in each phase, it tends to give the game a very different feel and offers new dynamics as the game progresses. And then, of course, you can use some of these mechanics specifically to adjust the length of each phase in order to make the game progress at the rate you desire. In Netrunner, the Corporation has some cheap defenses it can throw up quickly to try to transition to the mid-game quickly, and it also has more expensive defenses it can use to put up a high bar that the Runner has to meet in order to transition to the endgame. By adjusting both the relative and absolute lengths of each phase in the game, you can make sure that the game takes about as long as you want it to, and also that it is broken up into phases that last a good amount of time relative to each other.
Ideal game length
All of this assumes you know how long the game (and each phase of the game) should take, but how do you know that? Part of it depends on target audience: young kids need short games to fit their attention span. Busy working adults want games that can be played in short, bite-sized chunks of time. Otherwise, I think it depends mainly on the level and depth of skill: more luck-based or casual games tend to be shorter, while deeper strategic games can be a bit longer. Another thing to consider is at what point a player is far enough ahead that they’ve essentially won: you want this point to happen just about the time when the game actually ends so it doesn’t drag on.
For games that never end, like MMOs or Facebook games, you can think of the elder game as a final infinite-length “phase” of the game, and you’ll want to change the length of the progression portion of your game so that the transition happens at about the time you want it to. How long that is depends on how much you want to support the progression game versus the elder game. For example, if your progression game is very different from your elder game and you see a lot of “churn” (that is, a lot of players that leave the game) when they hit the elder game, and you’re using a subscription-based model where you want players to keep their accounts for as long as possible, you’ll probably want to do two things: work on softening the transition to elder game so you lose fewer people, and also find ways of extending the early game (such as issuing expansion sets that raise the level cap, or letting players create multiple characters with different race/class combinations so they can play through the progression game multiple times).
Another interesting case is story-based RPGs, where the story often outlasts the mechanics of the game. We see this all the time with console RPGs, where it says “100 hours of gameplay” right on the box. And on the surface that sounds like the game is delivering more value, but in reality if you’re just repeating the same tired old mechanics and mindlessly grinding for 95 of those hours, all the game is really doing is wasting your time. Ideally you want the player to feel like they’re progressing through learning new mechanics and progressing through the story at any given time; you don’t want the gameplay to drag on any more than you want filler plot that makes the story feel like it’s dragging on. These kinds of games are challenging to design because you want to tune the length of the game to match both story and gameplay, and often that either means lengthening the story or adding more gameplay, both of which tend to be expensive in development. (You can also shorten the story or remove depth from the gameplay, but when you’ve got a really brilliant plot or really inspired mechanics it can be hard to rip that out of the game just to save a few bucks; also, in this specific case there’s often a consumer expectation that the game is pretty long to give it that “epic” feel, so the tendency is to just keep adding on one side or the other.)
Flow Theory, Revisited
With all that said, let’s come back to flow. At the start of this blog post, I said there were two problems here that needed to be solved. One is that the player skill is increasing throughout the game, which tends to shift them from being in the flow to being bored. This is mostly a problem for longer PvE games, where the player has enough time and experience in the game to genuinely get better.
The solution, as we’ve seen when we talked about PvE games, is to have the game compensate by increasing its difficulty through play in order to make the game seem more challenging – this is the essence of what designers mean when they talk about a game’s “pacing.” For PvP games, in most cases we want the better player to win, so this isn’t seen as much of a problem; however, for games where we want the less-skilled player to have a chance and the highly-skilled player to still be challenged, we can implement negative feedback loops and randomness to give an extra edge to the player who is behind.
There was another problem with flow that I mentioned, which is that you can design your game at one level of difficulty, but players come to your game with a range of initial difficulty levels, and what’s easy for one player is hard for another.
With PvE games, as you might guess, the de facto standard is to implement a series of difficulty levels, with higher levels granting the AI power-based bonuses or giving the player fewer power-based bonuses, because that is relatively cheap and easy to design and implement. However, I have two cautions here:
- If you keep using the same playtesters they will become experts at the game, and thus unable to accurately judge the true difficulty of “easy mode”; easy should mean easy and it’s better to err on the side of making it too easy, than making it challenging enough that some players will feel like they just can’t play at all. The best approach is to use a steady stream of fresh playtesters throughout the playtest phase of development (these are sometimes referred to as “Kleenex testers” because you use them once then throw them away). If you don’t have access to that many testers, at least reserve a few of them for the very end of development, when you’re tuning the difficulty level of “easy.”
- Take care to set player expectations up front about higher difficulties, especially if the AI actually cheats. If the game pretends on the surface to be a fair opponent that just gets harder because it is more skilled, and then players find out that it’s actually peeking at information that’s supposed to be hidden, it can be frustrating. If you’re clear that the AI is cheating and the player chooses that difficulty level anyway, there are less hurt feelings: the player is expecting an unfair challenge and the whole point is to beat that challenge anyway. Sometimes this is as simple as choosing a creative name for your highest difficulty level, like “Insane.”
There are, of course, other ways to deal with differing player skill levels. Higher difficulty levels can actually increase the skill challenge of the game instead of the power challenge. Giving enemies a higher degree of AI, as I said before, is expensive but can be really impressive if pulled off correctly. A cheaper way to do this in some games is simply to modify the design of your levels by blocking off easier alternate paths, forcing the player to go through a harder path to get to the same end location when they’re playing at higher difficulty.
Then there’s Dynamic Difficulty Adjustment (DDA), which is a specialized type of negative feedback loop where the game tries to figure out how the player is doing and then adjusts the difficulty on the fly. You have to be very careful with this, as with all negative feedback loops, because it does punish the player for doing well and some players will not appreciate that if it isn’t set up as an expectation ahead of time.
Another way to do this is to split the difference, by offering dynamic difficulty changes under player control. Like DDA, try to figure out how the player is doing… but then, give the player the option of changing the difficulty level manually. One example of this is the game flOw, where the player can go to the next more challenging level or the previous easier level at just about any time, based on how confident they are in their skills. Another example, God of War did this and probably some other games as well, is if you die enough times on a level it’ll offer you the chance to drop the difficulty on the reload screen (which some players might find patronizing, but on the other hand it also gives the player no excuse if they die again anyway). Sid Meier’s Pirates actually gives the player the chance to increase the difficulty when they come into port after a successful mission, and actually gives the player an incentive: a higher percentage of the booty on future missions if they succeed.
The equivalent in PvP games is a handicapping system, where one player can start with more power or earn more power over the course of the game, to compensate for their lower level of skill. In most cases this should be voluntary, though; players entering a PvP contest typically expect the game to be fair by default.
With all of that said, let’s look at a few examples to see how we can use this to analyze games in practice.
Space Invaders (and other retro-arcade games)
This game presents the same skill-based challenge to you, wave after wave, and increasing the skill by making the aliens move and shoot faster and start lower. The player has absolutely no way to gain power in the game; you start with three lives and that’s all you get, and there are no powerups. On the other hand, you also don’t really lose power in the game, in a sense: whether you have one life remaining or all three, your offensive and defensive capabilities are the same. The player’s goal is not to win, but to survive as long as possible before the increasing challenge curve overwhelms them. Interestingly, the challenge curve does change over the course of a wave; early on there are a lot of aliens and they move slowly, so it’s very easy to hit a target. Later on you have fewer targets and they move faster, which makes the game more challenging, and of course if they ever reach the ground you lose all of your lives which makes this a real threat. Then the next wave starts and it’s a little harder than the last one, but the difficulty is still decreased initially. (You’d think that there would also be a tradeoff in that fewer aliens would have less firepower to shoot at you, but in the actual game I think the overall rate of fire was constant, it’s just how spread out it is, so this didn’t actually change much as each round progressed.)
Chess (and other squad-based wargames)
If I had to put Chess in a genre, yes, I’d call a squad-based wargame… which is kind of odd since we normally think of this as an entire army and not a squad. I mean this in the sense that you start with a set force and generally do not receive reinforcements, nor do you have any mechanics about resources, production, supply or logistics which you tend to see in more detailed army-level games.
Here, we are dealing with a negative-sum game that actually has a mild positive-feedback loop built into it: if you’re ahead in pieces, trades tend to be beneficial to you (other things being equal), and once you reach the endgame certain positions let you basically take an automatic win if you’re far enough ahead. This can be pretty demoralizing for the player who is losing, especially if you have two players with extremely unequal skill at the game, because they will tend to start losing early and just keep losing more and more as the game goes on.
The only reason this works is because against two equally-skilled players, there does tend to be a bit of back-and-forth as players trade off pieces for board control or tempo, so a player that appears to be losing has a number of opportunities to turn that around later before the endgame. Against well-matched opponents you will tend to see a variable rate of decrease as they trade pieces, based on how well they are playing, and if they play about as well we’ll see a game where the conclusion is uncertain until the endgame (and even then, if the players are really well-matched, we’ll see a stalemate).
Settlers of Catan (and other progression-based board games)
Here is a game where progression is gaining power, so it is positive-sum. There are only very limited cases where players can actually lose their progress; mostly, when you build something, that gain is permanent. Catan contains a pretty powerful positive feedback loop, in that building more settlements and cities gives you more resources which lets you build even more, and building is the primary victory condition. At first you’d think this means that the first player to get an early-game advantage automatically wins, and if players couldn’t trade with each other that would almost certainly be the case. The ability to trade freely with other players balances this aspect of the game, as trading can be mutually beneficial to both players involved in the trade; if players who are behind trade fairly with each other and refuse to trade with those in the lead at all (or only at exorbitant rates of exchange), they can catch up fairly quickly. If I were to criticize this game at all, it would be that the early game doesn’t see a lot of rapid progression because the players aren’t generating that many resources yet – and in fact, other games in the series fix this by giving players extra resources in the early game.
Mario Kart (and other racing games)
Racing games are an interesting case, because players are always progressing towards the goal of the finish line. Most racing video games include a strong negative feedback loop that keeps everyone feeling like they still have a chance, up to the end – usually through some kind of “rubber-banding” technique that causes the computer-controlled cars to speed up or slow down based on how the players are doing. Games like Mario Kart take this a step further, offering pickups that are weighted so that if you’re behind, you’re likely to get something that lets you catch up, while if you’re ahead you’ll get something less valuable, making it harder for you to fight for first. On the one hand, this provides an interesting tension: players in the lead know that they just have to keep the lead for a little bit longer, while players who are behind realize that time is running out and they have to close the gap quickly. On the other hand, the way most racing games do this feels artificial to a lot of players, because it feels like a player’s standing in the race is always being modified by factors outside their control. Since the game’s length is essentially capped by the number of laps, the players are trying to exchange positions before the race ends, so you get an interesting progression curve where players are all moving towards the end at about the same rate.
Notice that this is actually the same progression pattern as Catan: both games are positive-sum with negative feedback. And yet, it feels very different as a player. I think this is mostly because in Catan, the negative feedback is under player control, while in Mario Kart a lot of it is under computer control.
Interestingly, this is also the same pattern in stock car racing in real life. In auto racing, there’s also a negative feedback loop, but it feels a lot more fair: the person in the lead is running into a bunch of air resistance so they’re burning extra fuel to maintain their high speed, which means they need more pit stops; meanwhile, the people drafting behind them are much more fuel-efficient and can take over the lead later. This isn’t arbitrary, it’s a mechanic that affects all players equally, and it’s up to each driver how much of a risk they want to take by breaking away from the pack. So again, this is something that feels more fair because the negative feedback is under player control.
Final Fantasy (and other computer/console RPGs)
In these games, the player is mostly progressing through the game by increasing their power level more than their skill level. Older games on consoles like NES tended to be even more based in stats and less in skill than today’s games (i.e. they required a lot more grinding than players will put up with today). Most of these games made today do give the player more abilities as they progress through the experience levels, giving them more options and letting them increase their tactical/strategic skills. Progression and rewards also come from plot advancement and reaching new areas. Usually these games are paced on a slightly increasing curve, where each area takes a little more time than the last. As we discussed in an earlier week, there’s usually a positive feedback loop in that winning enough combats lets you level up, which in turn makes it easier for you to win even more combats, and that is counteracted by the negative feedback loop that your enemies also get stronger, and that you need more and more victories to level up again if you stay in the same area too long, which means the actual gains are close to linear.
World of Warcraft (and other MMORPGs)
Massively multiplayer online games have a highly similar progression to CRPGs, except they then transition at the end to this elder game state, and at that point the concept of “progression” loses a lot of meaning. So our analysis looks much the same as it does with the more traditional computer RPGs, up until that point.
Nethack (and other roguelikes)
There are the so-called “rogue-like” games, which are kind of like this weird fusion with the leveling-up and stat-based progression of an RPG, and the mercilessness of a retro arcade game. A single successful playthrough in Nethack looks similar to that of an RPG, with the player gaining power to meet the increasing level of challenge in the game, but actually reaching the level of skill to complete the game takes much, much longer. If you’ve never played these games, one thing you should know is that most of them have absolutely no problem killing you dead if you make the slightest mistake. And when I say “dead,” I mean they will literally delete your save file, permanently, and then you have to start over from scratch with a new character. So, like an arcade game, the player’s goal is to stay alive as long as possible and progress as far as possible, so progress is both a reward and a measure of skill. While there is a win condition, a lot of players simply never make it that far; keep in mind that taking a character all the way from the start to the end of the game may take dozens of hours, similar to a modern RPG, but with a ton of hard resets that collectively raise the player’s skill as they die (and then learn how not to die that way in the future).
Therefore, Nethack looks like an increasing player power and power/skill challenge over the course of a single playthrough… but over a player’s lifetime, you see these repeated increases punctuated by total restarts, with a slowly increasing player skill curve over time that lets the player survive for longer in each successive game.
FarmVille (and other social media games)
If roguelikes are the harsh sadists of the game design world, then the cute fluffy bunnies of the game world would be progression-based “social media” games like FarmVille. These are positive-sum games where you basically click to progress, it’s nearly impossible to lose any progress at all, and you’re always gaining something. More player skill simply means you progress at a faster rate. Eventually, you transition to the elder game, but from most of the games I’ve played this is a more subtle transition than with MMOs. FarmVille doesn’t have a level cap that I know of (if it does have one, it’s so ridiculously high that most people will never see it), it’ll happily let you keep earning experience and leveling up… although after a certain point you don’t really get any interesting rewards for doing so. But after awhile, the reward loop starts rewarding you less and less frequently, you finish earning all the ribbons or trophies or achievements or whatever, so it’s not that you can’t progress any further, but that the game doesn’t really reward you for progression as much, so at some point the player decides that further progression just isn’t worth it to them, and they either stop playing or they start playing in a different way. If they start playing differently that’s where the elder game comes in. Interestingly, the player’s actions in the elder game still do cause progression.
If You’re Working On a Game Now…
If you’re working on a game right now, and that game has progression mechanics, I want you to ask yourself some design questions about the nature of that progression:
- What is the desired play length of this game? Why? Really challenge yourself here – could you justify a reason to make it twice as long or half as long? If your publisher (or whoever) demanded that you do so anyway, what else would need to change about the nature of the game in order to compensate?
- Does the game actually play that long? How do you know?
- If the game is split up into phases, areas, locations or whatever, how long are they? Do they tend to get longer over time, or are there some that are a lot longer (or shorter) than those that come immediately before or after? Is this intentional? Is it justifiable?
- Is your game positive-sum, negative-sum, or zero-sum? Do any phases of the game have positive or negative feedback loops? How do these affect total play time?
Back in week 2, your “homework” was to analyze a progression mechanic in a game. In particular, you analyzed the progression of player power to the power level of the game’s challenges, over time, in order to identify weak spots where the player would either go through an area too quickly because they’re too powerful by the time they get there, or they’re stuck grinding because they’re behind the curve and have to catch up
It’s time to revisit that analysis with what we now know about pacing. This week, I’d like you to analyze the reward structure in the game. Consider all kinds of rewards: power-based, level progression, and plot advancement, and anything else you can identify as it applies to your game:
- Which of these is truly random (such as randomized loot drops), and which of them only seem random to the player on their first playthrough (they’re placed in a specific location by the level designer, but the player has no way of knowing ahead of time how quickly they’ll find these things)… and are there any rewards that happen on a fixed schedule that’s known to the player?
- How often do rewards happen? Do they happen more frequently at the beginning? Are there any places where the player goes a long time with relatively few rewards? Do certain kinds of rewards seem to happen more frequently than others, or at certain times?
Now, look back again at your original predictions, where you felt that the game either went too quickly, or more likely seemed to drag on forever, at certain points (based on your gut reaction and memory). Do these points coincide with more or fewer rewards in the game? Now ask yourself if the problem could have been solved by just adding a new power-up at a certain place, instead of fixing the leveling or progression curve.