My friends and I need an online co-op game for the PC!

Needs to support:

-Atleast three players

-Online (not LAN)

Some games we have played and enjoyed thoroughly:

-Terraria

-Minecraft

-Civ4

-Rainbow Six 3

-Baldur's Gate

-Neverwinter Nights

-L4D

-Killing Floor

-Garry's Mod

We like FPS and RPG mostly. I love RTS and TBS stuff, but the other two don't so much (It was pretty hard to get one of them to try Civ4, but he loved it. The other one refused to play it).

We didn't particularly enjoy Borderlands or Diablo 2, dungeon-crawlers in general we found sort of boring.

If you've got any suggestions, please post them!