Bloons Tower Defense (also Bloons TD or BTD) are a series of tower-defense games that were created by Ninja Kiwi. The focus of the games is to use towers to defeat an enemy called Bloons to progress through the game. As you play the game, the Bloons become more difficult to defeat. Players are able to upgrade their towers to help defeat stronger enemies. Bloons can come with power ups, such as camouflage and regeneration. Most of the Tower Defense games can be played on computers and mobile/tablets.