Many. Hard to pick a favourite.
VTM: Redemption. Society of Leopold
VTM: Bloodlines. The Hotel, Dr Grout, The Mansion, Death Mask studios, the latter for the scenery of all things: So seedy, so callous. This game pegs several horror sub genres so well: suspense, shock, gore...
Children of the Night II, a Morrowind mod. Hygina's interrogation is a very brief scene yet it brought me to a total halt while I questioned my own morals, even in a game, just how far would I go?
DA:O. Mage's Tower/ The Fade
FO3. Tranquillity Lane
Dreamfall: TLJ. New parts for Wonka, I'm a big old softy <chuckle>
Spellforce. The Rift, this was part of the demo and the reason I bought the game, an epic battle for a total novice.
Imperium Galactica II. The skirmish level King of The Ring
Almost the whole of Warzone 2100, much of Dark Reign and several parts, especially the limited unit levels, from some early C&C games.
Someone mentioned the original Unreal :thumbsUp: