It's been rainy for a week. Pardon the lack of energy.
I'm behind: I only heard about Perlin today.
What do I think? It's an idea. It's flawed as stated, but most ideas start flawed, and Perlin didn't state it - Ernest Adams did. So perhaps this should really be called "Adams' Corollary of Perlin's Law".
Perlin's law is good. Adams' corollary is a bit screwed up. My experiences in Nobilis tell me that there is no quicker way to break immersion than to attach numbers or costs to events. What he is essentially proposing is a "mana" to let you cast "spells" which break the game's reality in various fun ways. That's good for a game, but I don't think it's any kind of fundamental breakthrough.
The other problem, besides numbers, is the fact that you're breaking the foundation of a game's immersion with highly unlikely events. I don't think Perlin was talking about summoning chickens. I think he was talking about stumbling across clues to a kidnapping case. At most, he's talking about turning the corner and finding a chicken market.
There are a couple of other ideas which use the same principle without breaking immersion. For example, "for every action there is an equal and opposite reaction" would be fun. The more the player "spends" on unlikely actions, the more the computer can "spend" on unlikely actions. The player doesn't have to know how much he's spending. Of course, in this system, you still have to have a remarkable world engine to allow for such variability without forcing the player to carefully build whatever he's using.
Another idea is the "reality degredation" system, which is really a foundation to the rule itself. "The cost of an event in an interactive story should be directly proportional to its improbability." Well, obviously, once something happens, it's no longer nearly as improbable. Each time it happens, it gets more probable.
So, if a player does an unlikely action, it becomes cheaper for other players/AI to do equally unlikely actions. If the player wants to keep the game a serious real-world cop drama, he can. Or he can turn it into a melodramatic anime.
Also, world control could be given to a player, rather than an author, and the player could determine what is unlikely and what isn't, allowing for different "genres" of story fueled by one game engine...
But all of this is just silly chatter. These are not fundamental laws. They're just corollaries and fun gameplay dynamics.
The fundamental idea that Perlin is suggesting is that "the cost of an event in an interactive story should be directly proportional to its improbability."
I'm going to kick the tires.
I've written dozens of essays about player control, ranging from automatic adaptation to world set-up to game rules and on and on. To me, "cost of an event" isn't some kind of point value, it's the amount of attention a player needs to spend in order to even recognize that event as possible.
For example, a player is walking through a town. There is buried treasure in the town. The player finding that treasure is very unlikely. The longer the player spends in the town, the more people he talks to, and the more places he searches, the higher that probability becomes until, at some point, he finds the treasure.
Now, "that's a linear narrative! It's not generative!"
It could just as easily be applied to generative systems. For example, the player is passing through a city. The probability is very high that the city holds nothing of importance to him.
But every moment he dallies - every moment he talks to civilians ("Pro tip: talk to all townsfolk!") or breaks into someone's house - increases the chance that there's something important here. A "plot" event rather than simply idle conversation and breaking and entering.
Of course, to the player, this unfolds as: "You overhear the two men - they're talking about a pirate ship in the bay!" (Substitute cliche as you feel appropriate.)
To the engine, this is a progression: there's a lowish probability of providing a plot hook. Once you've provided a hook, there's a lowish probability of providing another plot hook based on the first. The longer that the player hangs out in "hooked" regions, the more times we "roll for hook deployment".
To the high-falutin' theory, this is simply "the cost of an event in an interactive story should be directly proportional to its improbability," where "cost" is defined as "player time/attention".
This has a downside of requiring you to write plots, or write something that can write plots. Of course, the downside to Adams' way is that you have to write something which allows the player to try to do anything with enough ease that players won't feel bogged down. Honestly, I don't know which is harder, but I've tried both and neither is easy.
I have some fun new ideas about those requirements, too, but not for this essay.
This essay is just a fun alternative to "cost" meaning "points".