Use your turret to blast the ball past the defensive line of the opposition. The enemy will try the same so this could become a tug of war over the ball.
Your turret will move around at the bottom of the screen, getting a proper aim requires that you constantly adjust the angle of your cannon. The points you have scored can be used to buy upgrades.
Hit the ball with your cannonballs to knock it towards the other side.
Make sure to score more points than the opposition.
Use the arrow keys to aim your turret.
Press space to fire.
You can buy upgrades after each level.