I think Puppeteer will become one of those games. I'm halfway through it and I'm already feeling like calling it a cult classic. I'm amazed at how clever the writing is. It walks the line between family friendly and adult so perfectly, like one scene where a guy compares a woman to a beautiful flower and says he wants to, "pluck her" tonight
It's visually amazing, fun to play, and very original. And cheesy as it sounds, the game has a certain "magic" to it.
The Viva Pinata games seem forgotten as well. I never hear anyone talk about them. When I hear people rave about the new Animal Crossing, it sounds similar in a lot of ways to the Viva Pinata games but gets far more attention. I've never actually played an Animal Crossing game though. Viva Pinata was really on the wrong console. A system built around tough guys with guns is no place for a cutesy, Nintendo feeling game like Viva Pinata
The Dark Souls games get raved about on practically every gaming forum you go to. I don't think they qualify for this thread.