Futuremark Oy has Unstoppable Gorg (iTunes Link) for the iPad in the iTunes App Store and Mac in the Mac App Store for FREE (was $4.99) for a limited time.

Space. The final frontier. Also, the place where you get to blow up evil aliens for the continued glory of your star-spanning imperialist overlords.

There’s a lot to love about Unstoppable Gorg. The immediate impression is that it’s a clever parody of 1950s B-movie science fiction, complete with black and white newsreel footage and bargain basement special effects.

That space rocket soaring through the stars? It’s a toilet roll wrapped in tinfoil and suspended on a piece of string, complete with a sparkler hanging out the back.

This enticement may well be necessary to make you lower your guard and have a go at yet another tower defence game. The genre has been done to death, sure, but take the bait and you’ll find a new approach that’s actually pretty darn brilliant.