In TimeShift, the player, Krone and Lin are members of a secret government agency that is developing a time travel technology. Krone betrays the other two, stealing the experimental time suit to jump into an alternate timestream and killing Lin in the process. The player puts on a second time suit that is more advanced but also more experimental and risky. He jumps into the alternate time-stream and goes after Krone.
Upon jumping, the player finds himself in the midst of a violent conflict in a city where Krone is supreme dictator. The player can plainly see that the insurgents aren't faring too well against Krone's forces. He allies himself with the rebels and fights alongside them through this unfamiliar world on his mission to find Krone, and ultimately return home.
Let's hope the game is as good as this new trailer: