A hair lip?

Design by Numbers: Simultaneous Perception

Perceived Simultaneity Threshold: 100 milliseconds

Let me tell you how I got my nickname, Jaime “Three Frames” Griesemer.

A hair lip?

Emily "Three Frames" Crazyhair

We were working on the melee animations for Halo 3, trying to get the timing right. There were already fast. Like, blink-and-you’ll-miss-it speed. The animators were having trouble because there wasn’t enough time to add a sense of anticipation and sell the impact properly. And for some unknown reason I wanted the damage keyframe to happen faster. “The melee animations can be as long as they need to be… as long as they’re exactly three frames.” We went back and forth about it, but eventually I traded three frame melee attacks for some extra flourish on the recovery after the hit. Everybody was happy.

Until the next day when I went back to try the new melee animations. I picked up the Assault Rifle. I pressed the B button. Three frames later, the butt of the rifle crunched into the face of a helpless alien invader. I picked up the Plasma Pistol. I pressed the B button. Three frames later, my left hook connected with a random marine that was looking at me funny. I picked up a shotgun. I pressed the B button. And for some unknown reason it didn’t feel right when I cracked open the head of a passing parasite. “Wait. That wasn’t three frames. Yeah, I’m sure, check the file. See… four frames!” (In hindsight, I’m lucky my uncompromising design demands didn’t earn me anything worse than a mocking moniker.)

What was the unknown reason? How could I tell the difference of only a single frame? Why did I insist on the speed at the expense of animation quality? The answer lies in our physiological limitations. What we experience as consciousness — as a stream of consecutive events in a clear and tidy order — is not nearly so neat. It’s a cacophony. A discordant mess. Your senses collect an incredible amount of information; they’re always on, always filling your nervous system with an unrelenting torrent of unfiltered data. It comes in at different speeds and at different times. The visual part is heavily processed, so it comes in late and is usually out-of-sync with the rest of your senses.

Change your mind?

Your brain at work

Your brain is used to this. It is, in fact, extremely good at taking all that information and combining it into a coherent experience. So good, it can take distinct events and merge them. Asynchronous events like pressing a button and seeing a melee attack. This feeling of simultaneity greatly increases the player’s connection with the action on-screen. Instead of a second-hand signal that transmits their intentions, pressing the B button becomes the act of dishing out a knuckle sandwich. But that requires your brain to blur over the delay and merge the movement of your thumb with the satisfying crunch.

Below a certain time threshold, the brain takes two events that are functionally separate — one causes the other and could not happen at the same time — and gives the impression that they were simultaneous. It turns out that threshold is around 100 milliseconds, or a little more than three frames. The reason four frames felt wrong was because the events were experienced as distinct, disassociated actions. The extra time allowed my brain to distinguish between them, in a sense inserting the controller as a step in the process and reminding me that I was not actually the one wearing metallic boxing gloves. So, for games where it is important to give the player a feeling of direct control, be careful of crossing the 100ms threshold.

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Against Iterative Design

“We practice iterative design”  You hear it in virtually every studio profile, every GDC design lecture, and it’s a buzzword game journalists equate with exceptional game design and a high level of polish.  Apparently there is a magic formula for making good games, and it goes something like this.

  1. Start with a fun game
  2. Make a tiny change (usually after exhaustive debate)
  3. Playtest extensively to see if those changes made the game better
  4. If they did, keep them; if not, change them back
  5. Repeat until your publisher makes you ship

It’s a pretty straightforward process, anyone can understand it and imagine executing on it.  Acceptance of this model leads to some pretty obvious ways to improve your design skills, too.  Make smarter changes.  Iterate faster.  Find better test metrics.  Take more time.  And now we know why Valve and Blizzard make better games than anyone else, right?  They take more time discussing changes, they have better tools for iteration, they playtest more than anyone, and of course, they ship when they are ready.  And it’s true, to some extent; a game that went through several rounds of polish will be better than one that didn’t.  But if you adopt iterative design as your primary design philosophy you will be doomed to making mediocre clones of better games…

First, let’s examine iterative design applied to other creative forms.  Want to write the next great novel?  Start with a book you really enjoy, like “The Count of Monte Cristo” and start iterating!  Pick a random chapter, change a crucial detail, and then read the whole book again and see if it is better.  Clowns are funny – let’s make Dantès a traveling circus performer instead of a sailor.  Over the course of 1400 pages, assessing that change is virtually impossible, except that the occasional clown-lover might comment on it.  Although no one change will be measurably worse, by the time enough alterations are made to create a substantively different novel, it will be an incomprehensible mess.

What a Dumas!

Pourquoi cet air si sérieux?

Let’s take a look at a concrete example of how iterative design can fail, specifically in determining the number of weapons the player can carry in a shooter.  In Wolfenstein 3d, the player could carry 6 weapons.  In order to improve this, an iterative designer would try playing through with 5 weapons and with 7 weapons.  Clearly, 7 weapons is better than 5 because the player has more choices.  So then the designer would try 8 weapons, which would also test better because “more” always tests better.  At some point, the designer would probably decide the gains from adding an additional weapon no longer justified the expense, and the game would ship with the player carrying 25 weapons at all times.  The iterative designer would never arrive at the solution introduced in Halo and adopted by virtually every shooter since, of reducing the number of weapons the player can carry, because the benefits of that system are not apparent until you reach 2-3.  In mathematics, this technique is known as hill climbing and it can only be used to find a local maximum because it cannot cross gaps to reliably find the global maximum.  Every designer knows that a game is never fun at first, so it is likely that even a good change is going to feel like a bad one for a short period of time, and an iterative process will reverse course too early.

Finally, a use for a math degree!

You can't get there from here...

The main reason that the iterative process is a siren song is implicit in Step One, “Start with a fun game.”  How can anything dramatically new be created if you are only allowed to start with something that is already successful?  If you something is already fun, stop iterating on it and work on the parts that aren’t fun.  And if something isn’t fun, the iterative process won’t get you there.  In the end, iteration is a polishing technique, not a generative one.

Shorting the Fun

Betting Against the Bank

A dizzying array of factors fed into the current global financial meltdown.  Sub-prime mortgages, anti-market regulation, credit default swaps, a real estate bubble, global conspiracy, global warming, alien sabotage… the list is endless.  But when it comes to the collapse of specific commercial institutions like Bear Sterns, it is pretty clear that short-selling accelerated or even guaranteed their failure.

A short sale (or shorting for… uh… short) is when an investor sells stock borrowed from a third-party with the intention of re-purchasing the stock and returning it at a later date.  If the stock goes down during that time, the investor gets to keep the difference as profit.  On the other hand, if the stock goes up they have to buy back the stock at the higher price and risk losing a great deal of money.  In March 2008, Bear Sterns (a global investment bank) became strapped for cash because it had over-invested in mortgage-backed securities and the bottom fell out of the housing market.  They might have been able to borrow the money to cover themselves, or at least gotten a bailout, but so many investors were short-selling Bear Sterns stock that it looked like collapse was inevitable.  This self-fulfilling prophecy ended with the company being sold to JP Morgan Chase a few weeks later.

Down with arrows!

Winning the race to the bottom

Shorting the Fun

Designers do the same thing, only instead of bringing down financial institutions, they bet against their mechanics and doom their game to mediocrity.

Take a Sniper Rifle, for instance.  Long and sleek, capable of putting a bullet through the head of a distant enemy faster than they can hear the sound of it being fired.  It has everything going for it.  Lethality to make it feel potent.  Precision to give it a high skill-ceiling.  A steady cadence with plenty of anticipation; each shot counts, but a miss isn’t a disaster.  Usable beyond the range of any counter-attack, even the hanging contrail it leaves behind is a testament to the thrill of each shot.  A designer couldn’t ask for a more perfect example of flow.

Then why do the Sniper Rifles in so many games suck out loud?  It just isn’t that hard to make a satisfying Sniper Rifle, so how do so many designers mess it up?  The surprising answer is that most Sniper Rifles probably started out fun, but at some point in development a designer got nervous about game balance and began to hedge their bets.  They made it less accurate, or decreased the damage, or added some weakness like an unstable crosshair or a really long reload time.  They were so afraid that they wouldn’t be able to make the Sniper Rifle work with the rest of the game, they shorted it and ended up losing a great deal of potential fun.

Still not a good idea...

Not to be confused with "fun shorts"

That’s how you get a Sniper Rifle that takes three shots to kill someone.  Or a tank that drives two miles an hour.  Or a spell that costs so much mana your mage can never use it in a fight.  Or any awesome and fun element with a crippling weakness that makes it all but useless.  Designers sabotaging their own games because they lost sight of what made something worth including in the first place!

  • Adding a Weakness – It may seem like the best way to balance an element that is too strong is to give it an equally large weakness, but it just doesn’t work out that way.  Either the weakness will not be enough, in which case you will have an element that is still too powerful and no longer fun to use.  Or it will be more than enough, in which case you will have designed an element that has a weakness as its defining feature instead of the original aspirationI would play as the invincible ninja character, but he has taken a vow of pacifism and doesn’t have any punches or kicks.
  • Creating a Counter – Another common way to address an overpowered element is to design a second element whose sole role is to counter the first.  Not only is this second element probably not fun on its own merits, but everyone will be saddled with choosing an option that they secretly hope they don’t have to employ, just to prevent everyone else from choosing the fun option they desperately want.  I will choose the unenjoyable anti-tank mine so that nobody else can have fun using a tank.
  • The Old Switch and Bait – Many games, especially those looking for a sense of progression, will initially introduce the player to a hobbled version of an element, and then unlock the truly fun version as a reward.  Of course, this ignores the fact that players usually won’t invest in a game that isn’t fun, and even if they do eventually earn the right to have fun, a vast majority of their experience will have been struggling through a crippled, unenjoyable game.  If I kill 300 more rats with this blunted shovel maybe I’ll get to use a real sword!… in this game that is ostensibly about swords.
  • Death of a Thousand Tweaks – Perhaps the most outwardly reasonable (and therefore the most nefarious) way of shorting fun is to make an endless series of minor changes, each one leaving the element a little less fun than it was.  Slightly less accurate, a touch less damage, a little longer reload, a smidge more recoil, a fraction less range, etc.  In this parody of the tuning process, the element gets gradually less fun until it is “unfun enough” to be included.  The problem is that tuning is more delicate than balance, so the element will lose the qualities that made it fun long before it becomes fair.  It will also leave players frustrated; if only this gun had been tuned better it would be really fun!

So, ignore the analysts and the pundits!  If an element or mechanic has the tiniest spark of fun, a designer’s job is to protect and nurture it, not smother it because it might out-shine the rest of the game.  No matter how tempting, there are always better options, so don’t short the fun!

So what are the alternatives to shorting the fun?



Definition: Tuned

Tuned  (See also: Polished, Tweaked)

A game mechanic can be considered tuned when it correctly constrains the player experience to have the desired effect

The opening four bars of “Smoke on the Water” by Deep Purple are perhaps the best example of the power chord.  Nothing screams sex, drugs and rock & roll like these iconic sounds.

Smoke on the Water

Smoke on the Water

 But if you play them even a tiny bit incorrectly, you’ll have a discordant mess.  Instead of the desired effect (impressing all the girls at the party) you will achieve the exact opposite.  In the same way, game mechanics must be precisely tuned to insure they work together to produce the desired experience and prevent undesired ones.

Not about war, either

A Fire in the Sky

Unlike balance, which must be considered across the entire community for the life of the game, a game that is tuned for one individual is probably tuned for most players.  That is because the tuning process constrains the entire possibility space, not a specific experience.  As it eliminates poor experiences and emphasizes or rewards the desired ones, the differences between player skill levels and choices are automatically included.