Quite an interesting take on the one bullet idea ! A couple of people have mentioned that at the beginning and start of each wave the bullet spawns too closely and at a random place to the player, I might suggest the bullet initially moves away from the player and then after a second or two revert back to following. This gives the player a few extra moments more to prepare for the bullet while also giving the impression the character is firing the bullet to begin. But other than that the controls are tight and the characters are charming ~