Thank you for your comment. I really wanted to do a game with more maths reasoning, but I tried to do that gameplay that you suggest; but the result was bored because I tried to do the circles slower and shoot the bullets with more time between bullets, but really that was not enough fun for me. So I thought shooting fast and to allow the player to shoot fast the bullets if maybe the player has not enough speed reasoning the multiple. But in levels more advanced is really important to reasoning fast, because just shoot bullets fast is not enough to survive.
About the sound; I am in agreement with you, the sounds are not to my liking. But I think is enough for the game jam.
Thank you again, for playing and comment.