Spring
Check out a recreated, updated version of the classic Chris Taylor strategy game Total Annihilation - now made to work on all modern PCs.
Total Annihilation broke barriers back with its original release about a decade ago, as it had you sending massive armies of actual 3D-modeled units against each other. While Chris Taylor has gone on to find decent success with the Supreme Commander games, the original TA community came together to make Spring, an open-source clone of the original with lots of new features, more moddability, and great gameplay.
The whole thing's not terribly easy to set up, as Spring technically isn't a game, but there are multiple full free strategy games that run on it. Grab the basic Spring package on this page and install it, then head over here to grab SpringDownloader, then run that, point it to where you installed the original package, click Downloader, and pick the mods you want. "ba" is Balanced Annihilation and is the most mature of all the Spring packages.
