[After a brisk nap]

The Secret of Monkey Island

I think it's outstanding in terms of richness and balance of gameplay, effective storytelling, integration of story and gameplay, pacing, puzzles, and extremely clever writing. As a swashbuckling tale, it really delivers the goods. Designed according to Ron Gilbert's at the time radical principles (now the template for essentially all adventures), it included innovations like no dead ends, no punishing the player, and a majorly improved SCUMM UI. And to top it all off with a twist of genius, there is Insult Swordfighting. The ending is a little bit anticlimactic (although the solution to the final puzzle is nicely ironic) and not as elegant as the LeChuck voodoo doll puzzle in MI2, but overall it's a triumph of game design that no other adventure game has come close to challenging.