It’s a simple enough idea. gmDoom is Half-Life 2 as is, right up until it isn’t. About a foot in front of the screen hovers a familiar, matt-black, double-barrelled shotgun. When it’s fired, it sounds like 1993 - but it turns out it makes holes in headcrabs and the Combine just as capably as its contemporary equivalents.
gmDoom is a partial source port of Doom, and will be available on the Steam Workshop is a few days’ time as an addon for Garry’s Mod 13. Mods on mods on mods.
It presents the player with a few options - shoot Ravenholm zombies with BFGs, whack cacodaemons with the signature crowbar, or relocate Doom wholesale to HL2’s environs. All three are represented in the video below, which you’ll want to watch:
Best bit: running betwixt the legs of a strider at 100mph and bringing it down with a hail of plasma fire. 1993 + 2004 = 2013 is the kind of dodgy maths I can get behind.
If you’ve any ideas for shooter mash-ups knocking about that skull of yours, I guess now’s the time to float them.