The listing, Paranautical Activity [Steam Key] has ended.
Paranautical Activity combines the classic FPS action of games like Doom and Quake, with the randomness and difficulty of modern roguelikes like Binding of Isaac and Spelunky.
More info: http://store.steampowered.com/app/250580/
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Get amazon gift cards and steam games just for play flash games ;D http://www.tremorgames.com/?ref=4043
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This game works on mac too!
Good Luck!