Sorry, I was actually talking about the Artillery tower. Got mixed up with AA tower. But still moving the collision sphere up is a pretty good move. It’s better than what I had in mind. I will probably do it that way when adding an AA tower to the toolkit.
As for the Artillery tower, I decided to make it kind of unique when compared to other offensive towers. So instead of just increasing the damage output per shot with upgrades, it will launch more explosive projectiles with each upgrade. You can adjust the impact location offset range, so that the projectiles don’t all land at the same spot.