Thank you! I'm glad to know that you see the theme kinda fits.
As for the upgrades, it may not be a bug, but an unexplained feature. So to upgrade from 0 -> 1, you need 1 star. 1 -> 2 requires 2 stars. So that's why your click isn't taken into account. I should've added a "You dont have enough star" pop up to explain that.
As for the freezing of the game, I'll look into it. It should freeze everything except for the restart button