Ditto on the ranged units being OP. I got to round 15 using only ranged units because they could shoot through walls and buildings. For the patrol path I made a small point rather than a path because for all the rounds up until 15 the spawners would be mostly on the same side of the castle. I hade fun gaming the system regardless!
We haven't even thought about buildings blocking arrows - that could be nice! Thanks for the feedback!
And for the spawners, we just repeatedly take a random angle for the spawn direction, which was good enough for the game jam, but I'm guessing overlaps were inevitable with such an approach. :D Definitely on our TODO list.