Thank you! it fills me with confidence that you think the game is well presented based on the source material :)
I am glad you have suggested the damage multiplier because it is already in the game and works really well! I made the damage double each circle the player draws, x1, x2. x4, x8, x16 damage each circle they complete. Like you said, it adds a risk element where playing safe with one circle does low damage while more circles save time by dealing bigger damage (if you can pull it off) with the levels being time sensitive its a great reward.
Some enemies also play into this, the sheep enemy multiplies every time it is hit (like a Hydra but cute) so single circles will make it harder to defeat but a 'triple circle' could take it out in one go
Thank you for your kind words and input :)