Freedoom is a free first-person shooter under continuous development. The Freedoom project aims to create a complete free content first person shooter game by using free levels, artwork, sound effects and music. Freedoom can't be run on its own. It must be paired with a compatible game engine (any Boom-compatible source port based on id Software's source code to their classic game, Doom) to be played. Freedoom is actually three games in one, consisting of two single player campaigns and one set of levels intended for multiplayer deathmatch (FreeDM). As for plot, Freedoom uses the same story as in the original Doom and Doom II.
I'm a Swedish fan of the Imperial Stormtroopers (their 'useless' armor looks awesome!), hence my username.