Cheap Steam Game fun for multiplayer?

[ThaRealiZt]

Cheap Steam Game fun for multiplayer? 

I've just started Steam & at the moment all I have is:

1. Left for Dead
2. Skyrim
3. Fallout 3
4. Team Fortress 2
5. DOTA

Anyone know any good free and/or cheap (I mean really cheap sadly),
games that I can play with others? It'd be nice to play games with forum members.

[upset]

i don't really PC game but i own CS:GO, Garrys Mod, Boy and his Blob, and thats it haha.

Hopefully someone will help you out.