"'Know thy enemy, know thyself, know victory.'
As tactical advice, Sun Tzu's famous maxim applies to a majority of videogames. Knowing that Piston Honda blinks just before throwing an uppercut helps you know victory. Knowing that the mothership fires two small shots before throwing up its shields helps you know victory. Knowing how many whip strikes it takes to defeat Dracula helps you know victory.
But what about the kind of knowledge that transcends the tactical - the kind of knowledge that lets you truly understand your enemy's motivations and background, his hopes and fears?"
Kyle Orland plumbs the depths evil in game characters.
Sympathy for the Devil
Although a game engine may not be able to really take advantage of revealing the motivations of the antagonist, it may be used to create a motivational state for the player. If the antagonist is a jerk, then the player will have no issues putting him down. When the antagonist is someone who is trying to achieve a reasonable goal using morally questionable methods, the player can't necessarily view their actions as good or evil. If the designers can make the player sympathize with the antagonist, then branched conversations, a la KotoR, Fable or Neverwinter Nghts, can be tailored to give the PLAYER the choice between doing what they know they must do (stop the antagonist) and possibly doing what they WANT to do (not be so hard on a sympathetic antagonist).