Crossovers aren't all that uncommon in video games, but they're rarely as satisfying as we want them to be. Sure, it's fun to see Iron Man tussle with Street Fighter's Chun-Li, or watch Mario trade blows with Sonic the Hedgehog, but what would happen if characters from disparate realities just sat down and, y'know, talked? The Poker Night games might be the only ones to answer this question, and the second one has made a pretty slick transition to iOS.
Tower defense may be the most overpopulated genre on iOS today, but there's good reason for that. They're simple to develop, and although the App Store has plenty of 'em, they're still really fun. To separate themselves from the herd, Backflip Studios is tying theirs into cult-classic film Army of Darkness.