Wyrmsun, the free and open source retro-looking RTS just had a sizeable update with some great new stuff included. The game uses a modified version of the old Stratagus engine which has itself been in development since sometime in 1998. It’s a very retro RTS, with it feeling familiar to old Warcraft titles and other RTS games released around that time. With that in mind, it won’t be for everyone but I think it’s great. There’s multiple races, story-based scenarios, units earn experience and level up, a persistent hero feature and much more.