Yeah there are positions where you place the towers under the water; you can also place the towers right in the area where the goblins spawn off the ship, leading to them getting stuck.
Performance is pretty sluggish in some areas, and without looking at any source code, I'm going to go on a whim and say it's the result of multi-frame vector distance calculations? Lots of built-in Unity functions related to vector distances, like Vector3.Distance(), utilize square roots which are very slow if used every frame.
AI is pretty fidgety, with some of the goblins not moving upon getting to the island and some boats spawning and not doing anything.
Experienced one crash when the goblins reached the main castle
You can place towers in certain locations that bug out the AI
