Very addicting! Here's some suggestions to make better! :)
1-> Floating titles for more structures on water.
2-> Ability to save progress during level. I don't want to waste bloonstones, but I don't want to start the whole level over again!
3-> Lower experience level for monkey knowledge packs. It's going to take WAY too long to even get to level 5.
4-> More level variety.
5-> More upgrades for banana farms/storage tanks/banks
 "Bloons Monkey City"){kind=icon}
 "Burrito Bison Revenge"){kind=icon}