MegaGlest is an entertaining free (freeware and free software) and
open source cross-platform 3D real-time strategy (RTS) game, where
you control the armies of one of seven different factions: Tech,
Magic, Egypt, Indians, Norsemen, Persian or Romans. The game is
setup in one of 17 naturally looking settings, which -like the
unit models- are crafted with great appreciation for detail.
A lot of additional game data can be downloaded from within the
game at no cost.