There's something in human nature that makes it inherently intriguing to watch natural enemies go at each other. Cats vs. dogs, lions vs. hyenas, Hatfields vs. McCoys, monkeys vs. balloons— what, you didn't know monkeys and balloons were natural enemies? In their natural environment, wild balloons are silent, deadly killers. What does all of this mean? Well, only that NinjaKiwi's Bloons Tower Defense 4 is here at last, stepping over Bloons Tower Defense 3 and adding much more of everything we love!