Thank you for playing my game! As far as the first level goes, there aren't actually any defenses to place that level. I wanted the players to get accustomed to the controls of the player character. Level 2 onwards introduces defenses to place! And you're absolutely right, much of the foundation for my code was from the Glitch Garden segment of the old 2D Unity course that GameDevtv did. Obviously there are some variances but it was pivotal in helping me to work through the development.