It seemed like did not know how to create text in your program..... well sometimes like when you beat easy, i didn't really understand why you didn't use static text...
If you select a flagpost to send your minions to (flanking) then you can't exit that flagpole (except with selecting another flagpole)... really annoying that you can't send direct units to enemy :( 5/5
Turn off the music (not the SFX) and darts popping bloons sounds like a megamovie pop corn popper. And than lasers against bloons sounds like a messed up saw ?
You should be able to upgrade other things than weapons, like monkey agility, blop collecting radius, and greater special bloon (like super-bomb) chances to get them
I think we can all agree that the lightning tower is WAY too powerful and should be removed or the cost elevated if another game comes out. Makes beating the game very,very easy.
One suggestion to increase gameplay:
DONT USE LIGHTNING TOWERS. period