Gratuitous Tank Battles now has a demo! Blue's News noticed the appearance of the 'demo' icon on the Gratuitous Tank Battles site . Clicking on that will start the 71 MB download and give you a chance to play a few missions, design a few units, and get hooked on GTB's moreish blend of tower defence and carefully planned lane assaults. You can select an option that will let the AI steal your unit designs and use them against you, essentially letting you create your very own baby version of Skynet. D'awww.