I would caution against KOTOR unless you have very good luck or an XP install somewhere. Why? The game is horrifically unstable. It's performance is worse than SimCity 4. Mind you that's KOTOR 1. KOTOR 2 is a bit better. But not by much.
Offline games that I really like to play are : Call of Duty 4 modern warfare ...is one of the my favorite game. Another latest game I just completed that Max payne 3
Max Payne is not an offline game - it requires an Internet connection at start up to connect to that stupid Rockstar Social Club thing.
Touhou Bastion Recettear Costume Quest Amnesia The Dark Descent Auditorium (or basically any puzzle game...) Stepmania (or basically any rhythm game...) Braid Super Meatboy (or basically any arcade style game...) Half Life 1/2 Mirror's Edge Knights of the Old Republic Tower of Heaven (if you can find the download version) Cave Story I could keep going but I'm getting tired of typing ^^.