Merge cannons to get more powerful cannons in this merge tower-defense like game. Take down wave after wave of attackers to get coins to use to upgrade your shield or cannons.
Use the mouse or touch to drag and drop cannons. Place similar ones on top of each other to make another larger more powerful cannon. Drag them to an empty slot so that they can fire on the enemies. Upgrade guns and your shield to progress and defeat more powerful waves.