My only complaint is that some of the puzzles are incorrectly named. For instance you have to solve 3-9 before you can unlock 3-7. Though that is just a speck compared to how well this game was made. 5/5
I was at ~90% done, and now when I come back after a break it's stuck at the "Loading API" screen. I left it alone to do other stuff and it's been on this screen for 30 minutes. And yes, I've tried refreshing...
Having to click left/right to switch between what my workers focus on can get annoying. Have some kind of drop-down menu to quickly switch from one material to another; or just completely replace it with a scroll window.
You should rather make it so that instead of having so many units total, have it so that you have a limited amount of units per type. Otherwise you end up with a balancing issue where it is actually better to just delete all your current towers and replace them with the next towers up before you fully finish leveling them up.
||R|2,1,175,0||613,224,100,160,66,54,p,190,87,45,16,111,266,100,115,178,89,p,100,160,80,11,370,396,145,203,160,80,p,190,170,65,12,325,73,145,81,106,203,p,0,0,0,3|613|164|510|166|| .....Talk about "I meant to do that."