Multiplayer - Designing Games - page 192

In game theory, mixed strategies must be perfectly randomized. But
since humans can't make random numbers, we can't ever play true mixed
strategies. Our minds are full of well-studied probability biases. Asked to
write a random string of 1's and 0's, we consistently alternate more often
than we should. Long runs of one symbol feel less probable than they are.
When we've just lost with a strategy, our judgment of its value on the next
play is altered. Biases like this can be exploited.
This means that there is a game in predicting faults in other players'
mental random number generators. If you understand someone and you
are skilled at yomi, you might be able to tell when he has a 35% chance
of playing rock, even if he is trying to play 33.33%. And you can turn that
knowledge into a win. Again, this pushes up skill ceiling and enriches
decisions.
Yomi grows from the manipulation of information.
Making strategic decisions depends on having good and complete
information about the game. Players need to know what's happening,
what their opponent knows, what their opponent thinks they know, and so
on. All this information can be manipulated from both sides if the game
design allows it, creating opportunities for yomi.
There are three basic ways players can manipulate information.
First, players can seek information to improve their own decisions. In
strategy games, players send scouts. In social interaction games, players
ask their friends. In shooters, they stop and listen for footsteps. Tools like
Modern Warfare 's heartbeat sensor or StarCraft II 's scan ability support
this kind of action.
Second, players can deny one another information. In strategy games,
they kill scouts. In social interaction games, they interfere with others'
conversations. In shooters, they'll throw smoke grenades or radar scram-
blers. Players can even hide metagame information—tournament players
in both StarCraft and Street Fighter have been known to save their best
moves during early rounds, only to unleash them in the finals.
Finally, players can plant false information to deceive one another.
While other kinds of yomi are about knowing the mind of the opponent,
deception is about controlling it. Sometimes deception mechanics can be
explicit, as in phantom units in strategy games, or lying in social interac-
tion games. Other times, players will find ways to use normal mechanics
to deceive. For example, in a shooter, a player might open a door to plant