With the gun, you can sit inside the ball and just let it fire like a turret
there is some strategy to it though, I usually use golf balls with the softball upgrade to make a wall, and then the main ball with the gun upgrade is a last resort if any sneak through. (got at least to wave 50 with this strategy)
Like this?
yup, just like that!
you can do it even sooner with just one softball upgrade
