Play "Bloons Tower Defense 4" by placing different towers within each level in order to pop a stream of balloons before they reach the end of the designated path. Different towers use different special abilities, each of which costs a different amount. Players earn money by completing levels successfully.
The game "Bloons Tower Defense 4" follows the basic concept of a tower defense game, wherein players must defeat different enemies by placing sentry towers throughout a level. In the case of this game, the enemies are balloons, and the sentry towers are different types of monkeys or machines. During the initial steps of the game, players can choose a difficulty setting and map set to begin the various levels.
At the start of each round, players can purchase and place different sentry towers on the field. Each tower type has a different attack and its own attack radius. If any balloons enter into that radius, they trigger the tower's attack. The basic towers have a relatively short radius and fire at a somewhat slow rate. Once players place all of their towers, they can start the level and watch it play out with no further input. By completing different levels, players unlock new tower types that have more powerful attacks and fire at faster rates.