Elephants, on the other hand, NEVER forget

Design by Numbers: Cooldowns

Maximum Cooldown Time: 6-12 seconds

Purple hippos. Green puppies. Red monkeys. Short term memory is an interesting thing. Yellow birds. Blue horses. It can only hold around seven items (give or take a few, depending on your level of concentration.) Which means for some of you “Orange lizards” is going to drive the first animal right out of your working memory. This is why most game controllers have around seven buttons — White spiders, Pink fish — and most successful action games don’t even use that many. Player’s simply can’t hold all those options in their heads at the same time.

Elephants, on the other hand, NEVER forget

Orange elephants.

But the most important aspect of short term memory isn’t how many options player’s can remember, but how long it takes for them to fade. Or how short. Neurological research indicates that we start to forget details as few as 6 seconds after being introduced to them. After 300 seconds we are only half as likely to remember a concept, and after 10 long minutes… forget about it. (Sorry.) So that means, depending on your reading speed, you’ve almost certainly forgot the first animal by now.

This has a direct application in determining the length of cooldowns for abilities in action games. (In this context, a “cooldown” is the amount of time that must elapse after an ability is used before it can be used again.) The player stores the fact that an ability was used in their short term memory, and if the cooldown doesn’t expire before they forget about it, they may never use it again! It sounds preposterous, but how many times have you seen someone go through a tutorial on how to use an ability, use it successfully once or twice and appear to understand how it works, and then get utterly baffled when required to use it again just a few minutes later? How many times has that happened to you when playing an unfamiliar game? I know it has happened to me more times than I can remember. (Sorry again.)

So, if a cooldown prevents a player from using an ability for more than 6 seconds, there is a risk that they will stop using it entirely. An onscreen indicator that a cooldown has expired helps, but habituation and change blindness limit how effective an indicator can be, especially when it changes very rarely. Repetition helps, because it transfers knowledge of the ability into more permanent memory, but even this is tricky because with a long cooldown what the player will be committing to memory is the fact that the ability is unavailable, making them even less likely to use it. The options, then, are to use very short cooldowns — between 6 and 12 seconds — or rely on a very noticeable reminder when ability is available again.

You missed a spot.

Indicators have their own problems

For an action game, where onscreen indicators are not desirable, long cooldowns lead to mechanics that are often ignored and quickly forgotten. Maroon walrus.

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He's about to have an experience he won't forget!

Put to the Question

If you want to learn something, read about it.  If you want to understand something, write about it.  If you want to master something, teach it.

– Yogi Bhajan

Successful designers are those that have the discipline to edit their work.  Generating gameplay ideas is exciting and easy; discerning those with potential and removing the rest takes resolve and vision.  But you’ll never get where you are going if you walk down every road — you must cut!

Removing game elements is usually straightforward.  They are almost always part of a collection of similar elements, so they can be compared on an apples-to-apples basis.  They are often specific instances of a general system — the Assault Rifle is an instance of the Weapon system, the Goblin is an instance of the enemy AI systems — which means that most of the work that goes into them can be applied to other elements and isn’t wasted.  An element is associated with a certain amount of work that must be scheduled for the models, textures, effects, sounds and animations, so it is easy to measure its impact on the overall scope.  And finally, since an element is by definition discrete, it can usually be removed with virtually no impact on the rest of the game.

This guy's name is Needler

Some elements just don't fit in

“Is this mechanic going to be fun?” is a good question, but impossible to answer.  Prototyping can help, but it still takes discernment to recognize the potential in a prototype.  It also represents an investment of resources, which can bias the team toward keeping a prototyped mechanic that ought to be cut.  “Can we implement this mechanic?” is also a good question, but “can” is not “should” and “implemented” is not “tuned”.  “Has a mechanic appeared in another game?” is a useful question, but isn’t necessarily relevant to the current game.  “Does everyone agree this mechanic is good?” is a seductive, but destructive, question; it replaces a designer’s instinct with general consensus and will lead to “downhill design” where the only possible solutions are the easiest ones.  The single best question for determining the potential of a mechanic is “Can the player be taught to enjoy this mechanic?”

He's about to have an experience he won't forget!

Not everything is teachable

Answered honestly, this question has far-reaching implications.  If a player never uses a mechanic, it might as well not exist in the first place.  If a player fails to realize that a mechanic exists, it is too subtle or the game is overly complicated.  If a player refuses to learn a mechanic, it probably doesn’t fulfill a fundamental aspiration for them — they will never be interested.  If a player is unable to learn a mechanic, it is probably unintuitive or it clashes with other aspects of the game.  If the designer cannot distill a mechanic down to teach it, they likely don’t understand the mechanic themselves.  If a mechanic can only be learned through explicit tutorial, it probably has an awkward or obscure control scheme.  Any of these problems are fundamental enough to warrant removal.

On the other hand, if a mechanic can be taught effortlessly — or better yet, players discover it on their own — or if mere awareness that an experience is possible is enough to motivate them to learn how to access it, this is a sign that a mechanic is reaching them on a subconscious level.  This kind of mechanic can be integrated into their thought process and lead to a fluid flow experience.

GDC 2010: Design in Detail V


The second way to develop a sense of balance about paper designs is to look for anticipation. (Anticipation really isn’t the right word for it, maybe “Imperfect Predictability”?) If you make players guess, they won’t see the point and will quit. If you don’t give them a chance, they will feel controlled and quit. Balance means probable, but not inevitable, future events. This allows the player to anticipate them.


Don’t your players into ridiculous movie villains.


David Sirlin (sirlin.net) is a SF Champion and a game designer (and just happened to be in the audience when I gave this talk at GDC.) He calls this concept Yomi.
In an action game like Halo you don’t want players to engage in this kind of second-guessing. It will paralyze them from acting and end up in random guessing. The Sniper Rifle has one purpose; you know what someone with a sniper rifle is going to do. The role prevents you from guessing by allowing them to anticipate what is going to happen. If they are expecting an event, they can process it more quickly and follow the action better.


Successfully sniping confers no benefits. As designers, we throw around the term “Feedback Loop” a lot, but they are not always good because they lead to a game being overly predictable. Anticipation requires uncertainty, and feedback loops work against that.


The best thing about roles is that they help you keep things manageable by breaking the design into workable parts.


If you are using roles, make sure players always have other options. The Sniper Rifle is never your only option, so the entire balance never rests on one weapon. By using multiple gameplay channels you reduce the difficulty of your balance problem.


If you break up the balance into groups that do not require cross-balancing your problem becomes simpler. I won’t say that monolithic is always bad, just harder.


The Sniper Rifle is not on every map. This limits the number of possible interactions that need to remain balanced.


Imagine somebody is holding a gun to your head… There is too much to do, what are you going to cut! What are you going to do? How can you get control of your scope? By making the hard choices…


What are the hard choices in the paper design pass? Which mechanics will you emphasize? How will you engage the player’s imagination?


Producers, please insert your fingers in your ears at this time. Some of the best advice I ever got was “Once you are done, cut half” and I have never regretted doing this. I’m not going to say “Kill your babies” Now that I am going to be a dad, the term doesn’t seem appropriate anymore. How about “Put your babies up for adoption”?

To be continued…