Well get it all in one with Combat Arms from Nexon. Its a free FPS shooter that you can download. Its almost like counterstrike. You can buy guns, modify them. Put shit like silencers and scopes on them. All kinds of shit. They have a bunch of game modes. They have your typical CTF, Death match and domination type shit, but recently they just released a new "zombie" mode kinda patch where its like World at War where you just hold out in a bunker and kill endless waves of zombies. Or they have Co-Op type missions where you go and rescue hostages with your buddies and battle the computer. Its a legit game.
Download the game here
http://combatarms.nexon.net/
zombie mode
YouTube- Cabin Fever Combat Arms gameplay USA
Fireteam rescue hostage
YouTube- Combat Arms Fireteam Mode Gameplay HD Part 1
other shit
YouTube- [CA] Combat Arms Montage 3
Download the game here
http://combatarms.nexon.net/
zombie mode
YouTube- Cabin Fever Combat Arms gameplay USA
Fireteam rescue hostage
YouTube- Combat Arms Fireteam Mode Gameplay HD Part 1
other shit
YouTube- [CA] Combat Arms Montage 3
