The game is unfinished. There is no "end". After you complete level 16 of 4th world, nothing happens. No cutscene, not even a mere dialog saying "you won, you saved the princess" or something.
This shows how greedy the devs are: they did not even bother finishing the story. For that reason, I WOULD NOT RECOMMEND SPENDING ANY CENT ON PREMIUM ITEMS.
Please vote up to prevent people from being ripped off.
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I was worried for you as you didn't write for quite some while. I am glad to see you again. I was hoping for a bit more creativity, but this is fine.