Ingemar got me really excited thinking about the idea of such gameplay.

In theory it can be done by recording the player's actions in the game, then as you return (back at the same time) you could litterally end up playing against yourself. Though you wouldn't have that same interaction as if it were really happening. Basically your other version of you would simply ignore you. Unless you code the first REAL game time machine. lol I think you'd easily win the competition should you do something like that. At least for innovation and fun.

For a 4 week development period though, not sure if such complex game mechanics would be feasible though.