Phineas and Ferb live a carefree life in their cozy little house. But the trouble was attacked by hordes of various monsters that penetrate the houses and rob them. Our friends were not at a loss and in their workshop built an amazing weapon that could destroy hundreds of enemies. After that, they installed these guns on the roof of the house and began to wait for the appearance of enemies. You and I will help Phineas and Ferb: Backyard Defense help them keep their defenses at home. Before you on the screen the back yard of their house will be visible. Enemies will run through it. You need to wait until the weapon takes its charge and shoot at the enemy. So you will destroy them.