Remember Total Annihilation? While it had its setbacks (balanced unit design one of them), the game still holds up to this day. It led the way in the early wave of RTS goodness. (I should do a post on the whole history of RTS games. That would be fun!) Anyway, Supreme Commander came out, but it wasn't as good in many ways, and it had its problems too. (Like spending entire games zoomed out to icon view, which isn't very exciting at the end of the day!) Anyway, Total Annihilation is so old, the code has been used to start Sprung, an open source version of the engine. Zero-K is built using Sprung. One of the main things it has going for it is unit balance. Any commander can build any of the factories from the start of the game. This makes things interesting. When units hit the map and begin to battle, it's all about having counter-forces to what your opponent is building. Here's the description from their website: And a one-minute teaser video... Last but not least, I want to point out Shadowfury333. He casts games. The Zero-K RTS community isn't large by any means, but they have a core group of players that like to battle with huge robot armies. Here's a game with commentary on one of my favorite maps - Akilon Wastelands. I believe it's based on a map from StarCraft 2 - or maybe another classic RTS? Shadowfury333 does a great job describing the action going on in the games. You can even terraform the map to your advantage... If you're into RTS games, I recommend you check it out.