It's time to teach them a lesson they'll never forget. You will command a small squad of troops who are eager to meet all kinds of extra-terrestrial lifeforms... and kill them.
Devastro is, at its core, a level-based top-down shooter in which you control a squad of soldiers destroying ETs and blowing up their UFOs. Your soldiers level-up during play (in RPG fashion, and you may find yourself replaying a level in order to avoid the death of a character you've worked to upgrade); main weapons are guns and grenades, though you get to control some cool vehicles in later levels.
The combat is rarely as intense as in frenetic overhead shooters like Crimsonland or RIP, but Devastro has something those games lack: actual humor. It seems the Army isn't too keen on acknowledging the existence of UFOs, though it understands the importance of wiping out the alien invaders. The story is carried through a series of comic-book-like cut scenes at various points in the game, and is amusing enough to keep you engaged and eager to wipe out those evil enemy saucers Sir! That don't exist. Yes Sir! Ready for deniable action Sir!