Merge Defense is a fun tower defense strategy game in which you'll merge upgraded cannons to defend your kingdom from hordes of monsters. Click "Play" to get started. Proceed as indicated by the pen in the instructions. Hold down the left mouse button and drag one gun to another to get a more powerful one. Then click on the hammer at the bottom so that more weapons fall out on the field. Compose it for pumping. With each level, the monsters will become more powerful, so it is very important to constantly improve the guns in order to defeat them. To deal with the boss, use the super attack. Click on the icons on the bar at the bottom to activate cannonballs and ice slow.