The Last Express (I finished this a while ago but was reminded by reading Stamboul Train this month). It's... ambitious, and mostly successful at its aims; it's literally the only game I've ever played that's created a solid-feeling world that feels like more than just a setting for the game, and the characters have lives that feel like they extend beyond a single narrative. As a game it has its downsides - the puzzle format is frustrating, at least for me (a climactic sword fight on the top of the train sounds like an excellent idea, but implementing it as 8 quicktime events in a row makes it much less so. Having to replay the same timeframe over and over again when you get something wrong can also be irritating, though mitigated in that the game does make some efforts to send you back to where you made your last mistake). But as a work of craft it's beautiful, and the characters and scenes have stayed with me in a way that few games have.