A classic of worldbuilding. Even with effectively no interaction with other characters, Riven creates a living world that oozes character, history, and life. There's a very specific kind of enjoyment I get from learning how a new world works, and does this game ever deliver. The ecology of the islands, the living culture of the Rivenese, the dead culture of the D'ni, and the inner workings of the mind of a very evil man. Some puzzles admittedly suck, but so many more are well-integrated tests of your world knowledge and understanding, way better than usual adventure game fare.
Gold standard for puzzle games. Incredible clue-based puzzle design, really unique and interesting visuals and animations, all combined with an interesting story that sees you through to the end.