Steam has recently released Spiral Knights, a free to play MMO that runs on their network. Developed by SEGA, the game is available on both Mac and PC. It’s a quick download for 300MB.
Spiral Knights looks like a typical dungeon crawl game. It’s not pretentious and it’s loads of fun. And yes I have to reiterate it’s free!
Spiral Knights is a great little game. The pedant in me makes me point out though that it’s not developed by Sega. It’s published by Sega, and is developed by Three Rings. The company that make Puzzle Pirates and who recently got the license for Dr Who.