Final Fantasy series,
Fallout series (from 1 to New Vegas, yes, i love them all and if i would have time i would beat all of them one by one)
Minecraft (gets boring after a while, or when you have ended epic big project, right, but after a while its again AWESHUM.)
Counter Strike 1.6
Warcraft III
Red Alert 2 (imho one of the greatest strategies all over the world)