Wyrmsun is yet another game we totally missed, mainly due to it not appearing in the SteamOS + Linux new releases. Valve really need to fix games showing up in the new releases section if they add a Linux version to an existing release later on.
The game is actually open source, you can find the data here and the engine here.
About the game
Wyrmsun is a real-time strategy game which features elements of mythology, history and fiction.
In the Wyrmsun universe a myriad of inhabited planets exist. Humans dwell on Earth, while dwarves inhabit Nidavellir and elves nourish the world of Alfheim. These peoples struggle to carve a place for themselves with their tools of stone, bronze and iron. And perhaps one day they will meet one another, beyond the stars...
Find Wyrmsun on Steam now.