I've finished playing Betrayer, a title I wanted to look into for a fair few years. My thanks to GOG.com for salvaging it from falling into obscurity, even offering it as freeware - and I've been fairly impressed.
While I think the game has certain flaws or that its elements don't
always gel together in the most coherent, non-immersion-breaking manner,
it's still one of the more original first person games of the past
decade.