Futuremark Game Studio’s impending tower defense game Unstoppable Gorg plays with the genre’s mechanics in a neat way. Rather than having stationary defensive structures, your towers (in this case, satellites) can be moved via their orbits.
Beta testing is currently in place ahead of the game’s “early 2012” release for PC, Xbox Live Arcade, and iPad. Attached are the latest screenshots, plus a trailer which shows the humorous vintage-science-fiction look Unstoppable Gorg is going for.