Tower of Guns

Tower of Guns is an indie FPS that was developed and published by Terrible Posture Games via Steam. It was originally released exclusively on Windows, but was later ported to Linux and Mac OS.

Gameplay revolves around exploring and surviving a massive tower filled with dangers such as turrets and lava.

Official description
"Tower of Guns is a fast paced first-person-shooter for the twitch gamer... with a few randomized elements to keep it fresh with each playthrough. It's a short burst "Lunch Break FPS"... not unlike Binding of Isaac mixed with Doom 2. Tower of Guns was made by a guy named Joe (with his brother Mike composing the music)."