Good day everyone!

Im looking for a 4 player co-op game

It can be old or new but it need some kind of co-op system. You can list any type of game, adventure, fps, rts, rpg and so on.

Any suggestions?

castle crashers

Left 4 Dead, Syndicate, Payday the Heist
Unless you are thinking about split-screen, hot-seat type of thing.

TD - Dungeon Defenders
FPS/RPG - Borderlands, Borderlands 2
Aggravating - Magicka
aRPG - Torchlight, Torchlight 2

Brute Force (Original Xbox), Supreme Commander 1 & 2 (PC), Serious Sam series,
Halo 3 onwards (I think they all support 4 player campaign co-op), Far Cry 3,
Metal Gear Solid Peace Walker, Dead Island, Left 4 Dead 1 & 2, Battlefield 3,
Warhammer 40k Dawn of War 2, Borderlands 1 & 2, Guild Wars 2.

Just a few good ones off the top of my head :).

Over the net would be best i guess its okey with lan also as one would just use a lan software then.

Thanks for the suggestions everyone keep them rolling :>

I recommend you Magicka. Very nice and fun game,

IL2 - Everyone get in a plane and teach the Nazis a thing or two.
Darkstone - Action RPG goodness
Diablo 2 or 3 - Action RPG goodness
Neverwinter NIghts (quest together for endless hours -- you could also have 1 person build a world and DM it while 3 others play through it)
HAWX - You can co-op the whole game. Great fun for flying.

seconding Borderlands

Alien Swarm + community mappack

I can't reccommend Magicka enough, it's bloody good fun, especially if you don't like one of the players, so you can keep murdering them over and over while pretending it was an accident.

Torchlight 1 is just single player.

swat 4, one of the best 4 player co op, others are already mentioned

Yeah, that sounds like lot of fun, especially if you are the one being killed all the time. Can't wait to try it.