After seeing http://www.mmo-champion.com/threads/...es-of-all-time I thought that a counter thread might bring up some interesting discussion.
So here's the criteria, games that are either panned by the critics or playerbase that you absolutely loved, or games that you felt slipped under the radar and deserve far better recognition than they ever got. Just explain how you feel they were underrated, and how you believe they deserve better praise than they have.
There's a couple of games from the overrated list I'm expecting to see pop up in here, but it'll be interesting to see if any others show up too.