Steam
Europa Universalis IV
CS:Source CS:GO
Darkest Hour: Europe: '44-45
Dota 2
Garry's Mod
All Half Life's
Left 4 Dead 2
Red Orchestra 1 & 2
Team Fortress 2 & Classic
Arma 2, OA & Arma 3
Dark Souls 1
All Total War series except Rome 2
M&B Warband
Space Engineers
Terraria
Battlefield 2, Bad Company 2
Crysis Wars
GTA IV & EFLC
Just Cause 2
Other
War Thunder
Planetside 2
Runescape
Minecraft
Really any F2P
Sorry for the long list