hey i played your game a bit. I think the idea is neat and I really love the hand drawn characters! I don't really know what to say, because the game is not yet finished, but if you have time maybe after the player clears some levels you can show the required amount only for a couple of seconds before hiding it, hiding the "clear" option, or having a time limit for an extra challenge later in the game. These are all just suggestions for if you have extra time. You first just need to focus on finishing the original idea - finishing the characters you mentioned, sound effects, button visuals (maybe also in the hand drawn style?) etc
again - cool idea and a unique art style
good luck! :)