Zero-K is a FREE, multi-platform, open source Real Time Strategy game, which aims to be a dynamic, action-packed, hassle-free experience, full of clever strategies and constantly moving combat. Includes an epic scale, realistic projectile and unit physics, terraforming terrain and hundreds of unique and interesting units.
Here is one of Mosquito's screenshots of a Zero-K battle for your enjoyment.
Those bubbles off in the distance are from Shield Generators, and the building in the foreground is a Geothermal Power Plant.
This is a VERY close-up view of the game. Normally, the player is a bit further zoomed out. Also, I should note, none of the interface is shown here.
Stolen from: Zero-k.info
very nice one :D