Bloons Tower Defense 4 is the fourth installment of the popular Bloons Tower Defense series, released on BTD4homescreen3122012.png|The home screen when Bloons Tower Defense 5 iOS was released. Dfdzbvfdb.png|Logo Moab.jpg|a MOAB in BTD4. October 26, 2009. The game has many new features, including but not limited to improved graphics, new towers and new modes. This game also has an expansion, with new maps and Specialties, which affect the cost of certain towers.