Are you too scared to play Doom 3 all on your own? Then you might want to check out Allied Marine Squadmates: a mod for Doom 3.
This is a mod released back in 2008 for Doom 3 which I stumbled across yesterday while searching for something about the Doom 3 marine. Basically it allows you to play with bots that will back you up in the singleplayer campaign. You can mix and match them with different uniforms and such to tackle the demons, zombies, and other nasties.
“When looking for a little back-up in an un-forgiving world... "=AMS= United Forces" reports for duty!”
"With all Major Bugs Fixed ... Extra Features ... and New Marine Styles Added!"
"Squadmates are Back with a Vengeance! ... Locked, Loaded and Ready for Action!"
“Squadmate Update: Prepare for "Allied Marine Squadmates v.7.1.ufo" .."United Forces: Official"
“Allied Marine Squadmates UFO is a one of a kind "Special Edition AMS" mod offering!”
It almost makes me want to install the game again. Maybe I will.