Anybody tried out Terraria yet? I got this last night and love it. Never played Minecraft, but this is probably somewhat similar (although some might disagree).

http://terraria.org/
http://www.terrariaonline.com/

"Metroidvania" seems to be the common comparison; it feels like that, for sure - has that classic feel. It's only $10 on Steam, so it's totally worth the minimal entry fee. Haven't played multiplayer yet - they don't have Steam servers operational quite yet. I may put one up on my own server for a limited number of peeps once that gets working.

It's incredibly addictive. Started playing last night and ended up going for four hours - a rarity these days for me. It's always "just let me get a bit more of this resource" or "build one more room in my house" or whatever. Graphics are eye-catching...but the gameplay is pretty simple: build, explore, survive. There are epic bosses and dynamic "corruption" to fight, too, but I haven't yet come across any of that - just trying to survive and get defense up against the hordes, explore a little bit, get some weapons.