Red Dead Redemption: Sandbox style game placed in the old west. REally fun. tons of gameplay
Dead Space: This was the first game to actually scare me. get it!
Star Wars (Knights of the Old republic I and II): Both games are RPG based and will be perfect to play at your grandmas house.
Dante's Inferno: Such a fun game, especially if you know background information on Dante
Stevens Pass and Mt. Baker