Hint for faster grinding esp. in later levels: As soon as you realize you won't beat the stage, don't let your towers shoot at enemies that will escape anyways as you won't get XP for these. Just fly into them so you + your towers can shoot down some enemies instead of just damaging most.
wow i finished the game and it didn't even say "you won" or something, it just stopped spawning monkeys :(
Anyways my advice is focus on upgrading, an upgraded Ninja Star will take you a while in the beginning, add a fire ninja and you're set for a while.
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 "Monkey Tower Defense"){kind=icon}
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