sys_record and sys_replay are not capable IMHO to get what Sydan is asking for. The problem is, that these functions only record (or replays) the user input. It doesn't record the movement and behavior of other people, objects, physics calculations and so on. When travelling backwards in time, all this stuff has to be "reverted", too, in order to make the process of time stringent. E.g. in a soccer game if a opponent fouled you and you werent able to shot that goal you could travel back in time and runaround him to shot the goal.