How Perlin's Law Makes Gaming Credible

simoniker writes "Veteran game designer Ernest Adams has posted a new column on 'Perlin's Law' which suggests that all books, movies, and games have a 'credibility budget'. For games, both the designer and the player decide what happens: '...the story itself can only tolerate a certain amount of improbability before the credibility budget is exhausted, and the story is ruined.' According to this new law, named after Ken Perlin, who gave birth to the concept, games should not be infinitely wide-ranging or allow the player to do anything he wants."

Re:Zonk:

[Trespass]

Really, is that any worse defining yourself by your favorite bands or TV shows?

Oblivion/Morrowind, God-Mode, and Game Balancing

[serodores]

Take the cheats from just about any game. How often does playing with cheats 'take the fun out of it', and how often does it 'improve the experience'. Given a cheat that lets you go anywhere and do anything in a game, it's been my experience that more likely than not, it ruins the experience (unless the game is obsenely hard, which is relatively rare). That also lends itself to a game balancing issue. The more open-ended you make a game (e.g., Oblivion/Morrowind), the more chances you have for both bugs, and balancing issues. (With enough grinding, it wasn't hard to become a virtual god in Morrowind.)

Scope Constraints vs. Behavior Constraints

[DragonWriter]

'...the story itself can only tolerate a certain amount of improbability before the credibility budget is exhausted, and the story is ruined.' According to this new law, named after Ken Perlin, who gave birth to the concept, games should not be infinitely wide-ranging or allow the player to do anything he wants."

This seems to conflate two very different ideas, one of which is obvious, the other seems misguided. Clearly, if there are no constraints at all on what players can do, that's going to strain credibility, in and of itself (at least, if complete freedom isn't limited to a special distinct mode designed for editing the environment rather than intended for "playing the game").

But I don't see how an increasing scope is countradindicated, so long as items in the game are designed for credible behavior and reaction. Sure, infinitely wide ranging requires infinite programming to create credible behavior, but its a nonsense limit anyway, since you'd need an infinitely powerful computer to run the game, and infinite media capacity to deliver it, anyhow. "You shouldn't do things that are impossible" isn't really a necessary warning.

Re:True for TV?

[drinkypoo]

The story might be ruined, but the public will still pay you money for a totally incredible story. Just look at the lasting popularity of X-Files, which drastically changed its plotline every couple of seasons (first greys, then black oil, then super-soldiers)

You pretty well just proved that you missed the whole point of this theory. X-Files bounced around, but greys, the black oil, and the super-soldiers all fit very nicely into the same universe. X-Files requires you to suspend disbelief, but only so far; for instance, at least the stuff on the show is consistent with our current understanding of physics. (Thus, X-Files might be sci-fi, but Star Trek is not... But I digress.) Let me quote the article a tad.

Adventure was different from other computer games of its day because it didn't print a list of commands for the player to choose from. Instead, it simply put a prompt on the screen and said, "type anything you want to." It pretended that you could do anything. Of course, after five minutes of play you realized that this was an illusion; the game didn't really understand that many commands.

and

Ken Perlin's Law: The cost of an event in an interactive story should be directly proportional to its improbability.

and

But the more I thought about it, the more sense it made, and the whole concept started to break up the logjam in my head about the Problem of Internal Consistency. What is the unit of cost of an improbable event in a story? Its credibility.

In other words, the real issue is one of consistency.

Re:True for TV?

[Total_Wimp]

I never realized until this article, but this is the exact reason I tend to avoid games with a highly developed story lines. If you're "playing" a story, then you have to be restricted and, usually, you'll end up being restricted in some arbitrary way.

In Unreal Tournatment, Battlefield2, etc, the restrictions are static and well understood by the players. Even though they have a "story" behind every map in BF2, I couldn't tell you what it is because it's wholly irrelevant to gameplay and I never bothered to read it.

On the other hand, playing Black, even with as weak as the story is, I have to follow the course of action dictated by the specific place I am in the plot. Sure, I have the "freedom" to blow apart tombstones, but only because that's necessary to the plot. Similarly, I can blow apart walls, floors and ceilings, but not arbitrarily. Only where it's important to the plot.

I don't want to be guessing what the storyteller thinks it's important for me to do in any specific "scene". I'd rather have an internally consistant world and simply use my own brain to mold that world to my advantage in the game. That's relatively easy to do in competitive FPSs and a lot of other games with weak stories. The bettery your story is, though, and the more that designer is going to have to reign me in... and the more I'm going to have to avoid giving them my money.

TW