Riven

Really holds up. Pretty incredible.

While the pacing of this game is absolutely glacial, the way it uses its puzzles for world-building is fantastic, basing its entire structure off of "show, don't tell." Technically there's only a few puzzles in the game, but they're massive and intricate enough to maintain your interest from beginning to end. The way they're designed is absolutely brilliant and forces you to understand your environment in a nuanced way. The storytelling is a bit lame but features fantastic performances.