A nice tower-defense style game! I like the art style and the wave system, the UI needs some work though -
1) Make the tower hp slider non-interactable (in the editor you can turn off the interactable option)
2) You can't quit the game in the upgrade menu (set the canvas order layer for the pause menu higher than that of the upgrade UI panel)
Apart from that, a tutorial would be helpful for newer players (especially regarding weapon switching); overall good job!