The scalpel is a bit buggy to start but once you see that movement it means you have started the minigame, if you go too fast or go out of the line, it bring you back. I have to admit that I should've made it easier. There is a lot more gameplay after you get past that! Please reconsider :) If you get past that, beware of the loud sound from the skin split tool that you place on the skin :D
I will check out your game soon, it looks really fun as well!