This game is still under development, but it's available for early access either on Steam or in the Humble Store. It's a post-apocalyptic game about 9 mutants with different perks and skills (possibly more soon) trying to reach the Nuclear Throne. Basically it's a top-down shooter kinda like Binding of Isaac but with even lower success rate. There are lots of weapons, leveling and mutation system and huge frustration factor but despite all these the game is really fun.
Oh yeah, the developers frequently livestream the game and even the development, it's really interesting to see how one plays his own game.
If you have a couple of $$$ to spend, it's a good investment.