A free-to-play browser-based Flash MMORPG video game by the name of 'Realm of the Mad God' has recently been released, and is playable at: http://www.realmofthemadgod.com
Players can choose between Rogue, Archer, Wizard, Priest, Warrior, Knight or Paladin classes, each with their own unique equipment and secondary attack. You must team up with friends or stangers to defeat the 'Mad God' Oryx, who appears once 25,000 of his minions are slain and 50 Skull Shrines are defeated.
If a player is killed on the field, they will lose all of their items and experience, so co-operation and wariness of your surroundings is key to success. Game features are subject to change based on user input, so if you have something you want to see added or fixed, chime in by making a post on the RotMG forums or by emailing the staff at Wild Shadow directly.
Good luck!
RotMG Game: http://www.realmofthemadgod.com
RotMG Wiki: http://forums.wildshadow.com/wiki/realm-mad-god