Throw something at the white-armored troopers, and they may toss a grenade back. Or they might just put their hands up. Or they could do something completely new, each time the game gets played.
Video games used to come preprogrammed with canned movements that expert players eventually could anticipate and figure out. But recent advancements in video game design - and new game consoles with dazzling computing power - have endowed computer-controlled characters with a sense of self-preservation and unpredictability not seen even a year ago.