The Naval strategy game OilRush, that has long been in development, has officially been released by Unigine.
The game features a post-apocalyptic world where armies from all over are fighting for what oil is left. The game contains single player campaign, quick game and multiplayer (over Internet, LAN and Steam) modes.
Currently the game is only available for purchase for $19.95 at the UNIGINE Online Store for Linux, WIndows, and Mac OS X. It should be available in the Ubuntu Software Center in a few days.