The one where dude is all like a time traveler? you have to kill some evil face dude in three different times before he kills everyone else? anyone remember? if a cop kills him first then he comes back in someone elses body, or even your own.. No?
Ooh! I know of the game, but I can't remember the name either. It was something with "M", I think.

There were three different portals resembling time periods. You had to go to every single one of them and kill the bad guy, who would either be player controlled or AI. The bad guy would start off as a head. If the bad guy was killed by a NPC it would take control of somebodies body, which could be the player.

The goal was to retrieve different body parts so you could defeat the bad guy somehow, or something. Or was the bad guy trying to retrieve body parts? I forgot.
In response to Android Data
Is this a BYOND game?
A DOS game?
A PC game?
Living and Dead, By DDT.