A Great game, usually most tower defences are very generic but this one takes fun to a whole new level. The one I dislike about this game is the sheer volume of explosion and ice immune bloons, there are just so many of them and the explosions towers are so valuable early game it makes the game very hard.
The game needs more levels like the final one, at least 9 waves for every level. That way you defenses have a chance to level up. An upgrade tree would be nice and don't stop at level 3. Also maybe a mini boss at the end of every level but a huge boss that has much more health at the boss maps. Finally maybe one air based level per world as you hardly ever have to fight more than 2 waves of air creeps.
The game could be more balanced. Boulder towers to weak for only being able to attack the ground, Spear towers to strong, Arrow tower is also in my opinion better then the laser tower.
0/5 sucks you can't swith what unit you want to send out you canlt train more than one plus you can't hurt the flying guys and your shield can only die once while theirs can die 3 times BOOOOOOOO