Not Windows 8 compatible
Vlambeer (Super Crate Box, Ridiculous Fishing) created Gun Godz -- yes, with a "z" -- as part of the Venus Patrol website Kickstarter a couple of years back. Now, you can buy it standalone for whatever price you feel is appropriate, straight from Vlambeer.
GUN GODZ is a first person shooter about gun, gangster rap and the rich culture of Venus. Players try to escape the jail of a hotel, which is the only building on Venus and is owned by a record-label owner who happens to be the God of Guns.
If the description somehow doesn't sell you, maybe Patrick Hancock's old hands on account of its righteousness will.