Clone Time

You know what happens when you go back in time? Quantum physics and stuff. Like, there's another you in an alternate reality. Real mindblower, that's what it is. I promise you! But, worry not! This game solves all those paradoxes for you. It's not that difficult, really. You just bring all of your alternate versions... to this same reality! And... voila! This is a co-op... that you are gonna play with yourself!

Turn on a switch and that opens a door... but by the time you're at the door, it's already closed again! Doesn't matter, just go back in time and go directly to that door this time. The alternate you will go and tap that switch. And when he does, you're right there, near that door, with enough time left to go through it at your own leisure! Magic, right? Nope! Just quantum superposition or whatever sciency-fartsy stuff is needed to make this convoluted mess work. Ahem. Physics!