A few days ago, we released MegaGlest 3.7.0, the latest (and obviously greatest) version of MegaGlest, a real-time strategy game which is fully free (no restrictions, no ads, no crap) and open source. You can play MegaGlest against challenging A.I. opponents or with or against up to eight (human) players online. All of Linux, Windows, OS X are supported.
Please read more about it on Megaglest.org and watch the trailer: