Upcoming PS2 and Wii title Manhunt 2 (you know, the game that is being delayed because of ratings controversy over its violence?) will feature an ending based on in-game actions.
According to NGamer, (via Kotaku), the game's final level will be determined by your conduct in the rest of the game. So psychos who kill puppies and whatnot will get a "darker" ending then players who don't eviscerate the innocent.
TheFeed, having played the first Manhunt, don't think a lighter tone will help. The game is just dark. And dark games are okay for adults to play. Let's call a spade a spade and stop apologizing for the more violent faces of human nature. Ignoring things doesn't make them go away.
Kotaku: Multiple Manhunt 2 Endings