I'm referring, of course, to single-player co-op. What did you think I was talking about?
Currently sitting in Greenlight and humbly collecting votes is Time Rifters, a rather unique-looking FPS. Basically, you need to blow something up on every level, usually a big old monster. You get four lives to do so. But therein lies the twist: your four lives can exist, run around and shoot simultaneously.
So you plan out your attack using all four versions of yourself, deciding what weapons and upgrades to use, where to go and what to shoot, then take down your opponent strategically with the assistance of your "time clones," as the game calls them. It's really clever stuff, take a look:
With a name like Time Rifters, you might be wondering if this game supports the Oculus Rift. It does, yeah. It was developed for it, in fact, but it's just as playable on a monitor -- something you can experience yourself by trying out the demo.
Time Rifters [Steam Greenlight]