In The Mighty Quest for Epic Loot you must use your character to break into either other players or NPC’s castles to steal their treasure. Stealing treasure gives you the ability to then level up and defend your own castle, which can be attacked by other players who can steal a portion of all your gold and life force. You play as either the archer, mage, or warrior, who level up as you raid other castles.
It is pretty much the lovechild of Diablo and Tower defense like games, so if that just so happens to be your cup of tea, give it a shot.
Currently the game is in its closed beta and has no set release date yet.