10. FTL: Faster Than Light
This is only so far down on the list because it's a game quite a lot of people actually are playing, but it's still limited to the indie scene. A PC exclusive, FTL: Faster Than Light is an experience of staggering depth and replay value, and will most definitely please the hardcore crowd. FTL is part RTS, part exploration, and part spaceship management, with randomized levels and, get this, no saving. Well, you can save to exit the game, obviously, but once you're dead, you're dead. No reloading. You go back to the beginning. This may turn some people off, but the game is never frustrating or irritating. Every time you die, you just get more determined to beat the game and show that you can complete such a punishing and unforgiving game. Just make sure you play the tutorial first. FTL is available on Steam and GOG.com for $9.99.