The listing, Paranautical Activity: Deluxe Atonement Edition - Steam Game has ended.
http://store.steampowered.com/app/250580/
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.
-Unique FPS/Roguelike combination
-Procedurally generated levels
-Impossibly fast gameplay
-Hidden levels
-Over 100 items
-40+ enemies
-Ridiculous bosses
-Kick ass Dubstep soundtrack
The Deluxe Atonement Edition includes the following
-Developer footage & commentary, from prototype to pre alpha to full release!
-The Seafarers Guide; A pro guide with a nautical twist. Consult the pro guide to become the leanest, baddest, mostest bestest Paranautical Activity player you can be.
-1 new level type, 1 new weapon and 1 new item.
-Wallpapers baby!
GG