I'm sure many of our readers are huge fans of Age of Empires, then it might be worth your time to check out 0 A.D, which is a free open source strategy game that has some very striking similarities. It did originally start off as a mod for Age of Empires but then moved to it's own engine as a standalone game. Developed by Wildfire Games, you play as the leader of an ancient civilization who must gather resources to raise an unstoppable army against your enemies. Build buildings, create new citizens, gather resources and new army units in a brilliant open source game that's still in alpha development for both PC(Windows) and Linux!