Sound like anything you know? It did to Eric-Jon Rössel Waugh, as well, and his feature on GameCareerGuide is an excellently in-depth discussion of the open-ended, generally optional gameplay found in both games. It'll make you appreciate Animal Crossing more than you already do.
And since we're probably not going to get another chance to mention Shenmue on DS Fanboy, we'd like to suggest that anyone looking for a neat adventure game/RPG would do well to pick up a Dreamcast and a copy of the game. It's not everyone's favorite, but we couldn't have loved it more.