If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Shoot the enemies by using tanks and build the castle before enemies’ rushes in. Select the tank based on the amount and place it on the field. To shoot the enemies, place the tank on field and click on the enemies. Construct the castle by attaining the target in each level.
Arrow keys right / left - To move the tank.
Mouse key - To aim / shoot.