Alan Wake - Simply the best movie/theatrical game.
Max Payne 1 - The game i have played 100% so many times that i cant even count.
Max Payne 2 - This is just awesome sequel after part one.
Craftland (Minecraft) -
Call of Duty: Black Ops - Don't get me wrong, i dont play other CoD's, i havent played the Black Ops Multiplayer more than 10 hours, the singeplayer part of CoD:BO is just the only thing that attracts me.
Call of Duty: World at War-singleplayer only.
Runescape - Over 5000 gameplay hours, since 2004.
Battlefield 3 - Simply the best action-strategy-shoot 'em up game.
Crash Bandicoot 2-3
And many various other games too.
Age si quid agis.