Tower Defense is a strategic arcade game with the goal of defending your castle by placing towers that will defeat the enemies before they reach the end of the path. Tap on the spaces that allow towers to be built and select from the list of available towers. Collect money by taking out the enemies so that you can build more towers. Tap your towers to upgrade or sell them. Upgrades increase the speed and attack power of the tower. Clear all of the waves of enemies to complete the level. Run out of lives and it's game over!