Operation 137 is a DOOM 2 wad designed for GZDOOM with 9 maps and 2 Deathmatch maps (MP02 is unfinished). You can read the txt file included with the WAD to find more information.
Stationed guarding research base 137, some shit went horribly wrong. No seriously, you have no flippin' clue on what happened. As one of the most elite soldiers within 5km of the base, it's YOUR job to clean up whatever the hell happened here. You aren't a fortunate one, that's for sure. Get ready to enter the DANGER ZONE.
I don't download anything without screenshots and I know I'm not the only one.
I just put some photos in the description if you want to take a look