We ran out of time to make the towers cost resources and have the check for tower position validation - kept running into issues with the raycast not working with the colliders.
As you may have also noticed there was only 1 wave, I was trying to figure out a way to use the contents of a dictionary to spawn the waves but ran out of time.
Thank you for taking a look though - fingers crossed that for the next one we do we'll be able to get something more complete done.