Sergeant Mark IV (created original proof-of-concept, sprites and coding)
OSJClatchford (across the board resources) (that's LATCHford, not CLATCHford)
SidDoyle (gib sprites, mega coding help)
Almonds (spritework, coding)
Blox (resources for monsters, weapons)
Itsnaturetodie/David G. (resources for monsters, rifle)
Vader (resources for monsters)
Minigunner (resources for monsters, weapons)
Perkristian (smooth weapons)
Z86 (resources for weapons)
Eriance (resources for monsters)
Uboa (resources for weapons)
Blue Shadow (resources for weapons, massive coding help)
Mike12 (resources for weapons)
NeuralStunner (resources for weapons)
JoeyTD (resources for weapons)
Turbo (resources for shell casings)
Marphy Black (resources for monsters)
Zrrion the Insect (resources for props, textures)
Chickenlegz (resources for monsters)
Agaures (textures)
Taggart (helmeted zombie sprites)
NiGHTMARE (textures)
Solmyr (resources for monsters, chain lightning)
Monolith (resources, sounds for shell casings)
Valve (sounds for shell casings)
3D Realms (resources for explosions)
Doom4Ever mod (resources for barrels)
Xim (alternate zombie faces)
OnslaughtSix (mugshot work and general helpfulness)
Osiris Kalev (bugfixing help and putting up with my bullshit)
PK1 (inspiration and general helpfulness)
Shadowy Men On A Shadowy Planet
Man Or Astro-Man?