In no particular order:

Counter-Strike 1.6
Starcraft Brood War
Heroes of Might and Magic 3
Age of Empires 2
Diablo 2
Terraria
Super Smash Bros Melee
Worms Armageddon
Elder Scrolls Morrowind, and Skyrim. I have a soft spot for Oblivion but it's pretty bad
Fallout New Vegas
Dragon Ball Z Budokai Tenkaichi 3
Halo 3 / ODST / Reach
Metal Gear Solid 3
Metal Gear Rising Revengeance
Pokemon - Everything up to the 3ds games my favourite is Platinum
Dwarf Fortress
Castle Crashers