Freedom Fighters was really fun. any of the Thief series, Gabriel Knight games, Planescape: Torment, beyond good and evil, Silent hill 2, RE 4.. best on that list is Morrowind though.. amazing game, even with the (now) outdated graphics
EDIT: Rune: Halls of Valhalla, Baldur's gate, Grim Fandango, Vampire the Masquerade: Redemption and Bloodlines (though you'd need some of the uofficial patches)