Controls (listed on the game page itself, did not realize they would not be displayed with the submission by default):
WASD/Arrow Keys - Movement
Left Click - Spawns a Tower at the cost of 50 Points, and makes the controls move the Tower instead of the camera.
Right Click - If a Tower is being controlled, fixes the Tower in place and returns controls to moving the camera.
(If there are any inconsistencies, I probably overlooked a control change during development and would appreciate if you let me know so I can update this comment.)