9. Nier
If you've played this game, let alone heard of it, you are serious gamer, and rewarded yourself with nice bitter yet clever ending. If you stick with it for 3 outings, you'll be privy to an original and refreshingly sour conclusion. You've stuck around for a while and the villain of the piece has noted this, and this time gives you an alternate ending: save your pal and erase yourself from existence. Completely- including your save game- or don't and your friend stays all possessed. It's once in a life-time ending, the developers using the technology to create a choice that will actually affect the gamer too, not just the character. Forcing you to make a choice to sacrifice hours of hard work for the sake of a happy ending. Brilliant stuff. One of the best endings you've never heard of.