'"No More Room in Hell' is a free to play HalfLife 2 mod. It's a multiplayer, 8 player co-op survival horror game with a focus on semi-realism. It was inspired by the 'Of The Dead' zombie franchise which is were it gets its namesake." - The Devs
This mod is very new, and has a number of very obvious problems, but it is a work in progress and I believe it has a great deal of potential. There are a large variety of weapons that the average citizen would be likely to possess and ammo is scarce. In my playthroughs I've used an M9 Beretta, Colt 1911 NM, SW 686, Remington 870 Tactical, Beretta SV10, Sako 85, and SKS, and I'm sure I haven't used them all. The maps are very dark and you must use a 3D Maglite to get through a lot of sections, but when you have it equipped you can't carry a pistol Chapman or Ayoob style (but that doesn't stop you from cranking a few zombies in the face with it.) Overall, I enjoyed it and for the price of FREE, there is little to complain about.
Official Site with download:
http://www.nomoreroominhell.com/
Trailer:
