TouchArcade: If you think you're all Tower Defense'd out, be prepared for the tables to turn. Ayopa Games have set their sights on a time honored genre that is, to be honest, usually pretty outdated. Sleep Attack TD[$2.99] is their first foray into tower defense. Our forums have been buzzing about this game for good reason. With the bright asthetic Ayopa is known for and some very unique gameplay, Sleep Attack brings some much needed defibrillation to a category of games that seems to be in constant danger of completely flat lining.