Suggest me good multi-player games

Hearthstone

Tibia

Transformice

Dead island : Epidemic ,,
How to survive (COOP/SP) ,,
Awesomenauts ,,
Airmech ,,
Magicka : wizard wars (its now open beta on steam).

Play all valve games again xD

Nosgoth, which you can get into the beta for free by registration on their website. GMG also has a sale on the Veterans pack Nosgoth for $7 USD. Fistful of Frags is also good.

Dota 2

Red Orchestra 2, FoF, Solstice Arena, Awesomenauts, StarWars Battlefront 2.

Don't play too much multiplayer games off steam apart from some browser games and Hearthstone, so don't know too much about that.

Verdun

Fistful of Frags.

Mount and Blade Warband

Battlefield 3 is free right now. Burnout Paradise was in a bundle a while back and last time I played I was able to find a game. Fistful of Frags is new on Steam and Free to Play, so you can try that, it's quite alive. GMOD. Just Cause 2 Multiplayer mod is a must, and JC2 is often on sale for like 3.74. Rising Storm/Red Orchestra was free, although Rising Storm still has to be bought. Unreal Tournament is surprisingly still active.