I'm trying to bulk up my Dreamcast collection, and one game I've always been curious about, is Phantasy Star Online. I've always heard it described as an MMO though. But I've learned it has a single player mode. Also the Ver.2 version isn't very expensive. How integral is its multiplayer aspect to its experience?
I've also learned there's an enhanced version on the Gamecube (that appears to cost a fortune), and apparently the only multiplayer it has is 4 player split screen. Is PSO really more of an online co-op game then an MMO? Its a bit unclear.