A very unique experience! Great job making everything yourself. The slingshot gameplay is fun. :)
I can see part of the challenge being spacial awareness, knowing where your target is without directly seeing them, but this causes problems when you have absolutely no idea, example being Round 1 where you'll always be firing blindly. If there were, for example, an arrow pointing in the general direction of Derduck's location it could help mitigate that a bit.
The music clip is quite short, so it gets repetitive quickly.