Nice! It's simple and charming. Liked the humor and decor
In the info book it shows the effect of upgrade with an animation, it's cool but the poison and electricity one looks like they do nothing. Also only the last one, the gear, shows at higher upgrades
I had to watch the monster health to better understand poison and fire, but I could only guess the effect when stacking the upgrade or with how much it hits the same target. Like is two poison upgrades on the same tower stronger than on two different towers?
It's also hard to understand when the invisible enemy becomes invisible
The game wasn't easy so this information of the mecanics can matter when you need better strategy I think