http://www.realmofthemadgod.com/ (you can play it in your browser right now)
Immediately I felt at home because of the retro graphics and simple controls. Seriously, this game is pretty simple and its a refreshing experience. You start out as the Wizard class and its a fun class to play. You can unlock other classes by playing the game. Yesterday I unlocked the Priest class.
One thing you need to know is that death is permanent. I died a few times but once you get used to how it all works, staying away from death isn't too bad. I did find that since death is permanent I was playing it safer than I do in other games. I only made it to level 5 and its not hard to get back to that level.
Check it out, its fun a best of all: free.