killer7 is still one of my favorite games of all time, but I'd rather watch it again than play it, unlike most of my other favorites. As a game, it's not much, but it's what if offers outside of gameplay is what makes the whole thing a very unique and unusual trip. The game's storyline is very incomprehensible, disjointed, paradoxical... yet is quite intriguing and fascinating at the same time. It made me think a whole lot without making the game trying to make me swallow the whole thing like some lecture (which other games tend to do when they're trying to prove some philosophical point).
Now if a lot of games would gladly take risks and let their creators get free reign to go crazy with their creativity, we'll have a lot more unique games out there.