I tried to play, but in two browsers got the same issue - the game loads up and I can read the How To Play. But as soon as I click a tower, it never lets my cursor go, and I can neither place the tower anywhere nor go to the main menu. So functionally, I cannot play the game at all.
Interesting concept for sure.
When NOT setting to fullscreen, the screen doesn't fit in the browser view, so fullscreen is a must. But it still didn't work, either way. Best of luck though. Cheers ^_^