What are the best online multiplayer games?

Counter Strike!

Counter-Strike: Source

Left 4 Dead 1+2

Killing Floor

with Day of Defeat: Source coming in at a close 4th.

PAYDAY.

Worms: Reloaded

I really enjoy CS 1.6 and TF2 and Mount & Blade: Warband

Borderlands.

Payday the Heist
Killing Floor
L4D2

cod

Zero Gear

Dungeon Defenders

Torchlight 2

Payday, Killing Floor, & The Secret World are my 3 favorites on steam.

Natural Selection 2 is the current game I'm obsessed with.

LoTRO and TF2.

i been havin a blast on:
Shogun2: Total War
CS:GO
Guns Of Icarus Online
edit: maybe not my alltime favs but just the 3 im playin atm

garry´s mod

Dota 2 , Tf2 , Cs 1.6 or Cs:GO , Killing Floor..and Payday according to me these are best multi-player game.. If u are COD fan u may like cod multi-players.... Bt Battlefield 2 Bad company and Battlefield 3 Gamepay is far better then COD

COD:MW2

All Valve Games
Garry's Mod

at the moment:
Red Orchestra 2 and
Age of Empires 2 HD (I seriously hope they fix the performance problems one day -.-)

Chivalry

Dota, L4D, probably some CS as a third. :P

Battlefield 2
Dota 2
Garry's Mod

Team Fortress 2, Battlefield Bad Company 2, Borderlands 2

League of Legends if you like strategy/action/thinking.

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