Doom was released in 1993, so most guns in the game that didn't have the word fucking in the middle of them are looking a little antiquated by now.
To give the game a more contemporary - dare I say Modern - touch, some enterprising souls have released a mod for both Doom and Doom 2, bringing pixellated versions of Modern Warfare's arsenal (and a suitably green HUD) to the 1990s shooters.
You can see it in action in the clip above.
UPDATE - We've removed the links to the mod because it contained pirated copies of both Doom I and II. Tsk tsk.