Free open-source game like Age of Empires 2

0A.D. A free open source game which is based on Age of Empires 2. I am not advertising or anything but more people gotta get to know about this game, it haven't been released yet but there is a free alpha that you can download and try it out.

 

http://play0ad.com/ website

http://www.youtube.com/play0ad gameplay and updates

looks pretty cool actually