In no particular order...
Baldur's Gate 1 + Tales of the Sword Coast
Baldur's Gate 2 + Shadows of Amn
Planescape: Torment
Icewind Dale 1 + Heart of Winter
Icewind Dale 2
Fallout 1
Fallout 2
Fallout 3 + All the DLC
Fallout Tactics
Elder Scrolls: Morrowind
Elder Scrolls: Daggerfall
Vampire: The Masquerade: Bloodlines
Vampire: The Masquerade: Redemption
Mass Effect 1
Mass Effect 2
Jade Empire
Dragon Age: Origins + DA: Awakening
Knights of the Old Republic 1
Knights of the Old Republic 2
Neverwinter Nights + Shadows of Undrentide + Hordes of the Underdark
Neverwinter Nights 2 + Mask of the Betrayer + Storm of Zehir
The Dark Eye: Drakensang
The Last Remnant
Final Fantasy 9
The Witcher
Fable
Freedom Force
The Temple of Elemental Evil
Lionheart: Legacy of the Crusader
Arcanum: Of Steamworks and Magick Obscura
Anachronox
Septerra Core: Legacy of the Creator
Diablo 1
Diablo 2 + Lord of Destruction
Titan Quest + Immortal Throne
Torchlight
Dungeon Siege
Dungeon Siege 2
Nox
I may have forgotten a few...
Also, a bunch of older games such as "Eye of the Beholder" series, some "Might & Magic" games, the "Gold Box" D&D games, etc.
As you might have guessed, RPGs are my favourite genre...
