Doing some more searches of the forum I can't find any mention of the game at all so just a quick bit of info:
Realm of the Mad God is a very simple 8-bit style browser MMO that is available here: Realm of the Mad God
or via steam. Both versions are free.
The pace of the game is quick, uncomplicated, and has a real retro feel to it. Left mouse button attacks, spacebar delivers a special attack based on your class. New classes are unlocked by leveling the base classes up. Max level is 20, and a knowledgeable player can hit it in an hour of play. The interesting part is permadeath, hence the quick leveling. Once you die you can create a new character and hop right back in, but all of your gear is lost.
Its a fun, free browser MMO that is nice in small doses, but gets grindy and repetitive if played too much or too often.