Awesome concept! it's cool how a simple twist like "what if you bought upgrades with keys instead of gold coins" already feels like an interesting world. Loved the little hamster character and the intro cutscene. Gameplay felt like a standard idle TD but I think I wanted a little more like the kind with active clicking +1 key per click, or deal damage to enemies by clicking on them too.
I ran into some problems at first building two cannons on the left and then discovering there's a right side being attacked... I think it should be a bit more forgiving so I could recover without game over right away. Most TD games you lose a life per enemy that reaches... so if I lost 3/10 lives instead of Game over, i could have adapted and kept going into level 2!
Then that brings me to the technical aspect which was the main problem replaying. I think a few variables weren't getting reset: the central key level stayed, and the cannons I built became unclickable spots. Eventually all slots got blocked and the game ended as soon as the monsters spawned.
I'm very impressed @tbleazy got to level 20!? Now I'm curious what is the optimal build order to get past the first few lvls