thank you for your Feedback :) it is Indeed a Gameboy Game. After the Jam I will Upload the Rom file so it can be played on a real Gameboy or an Emulator :)
Yes it is Not a Bug. If you bite an Animal it gets red eyes and appears constantly on the screen to show, that you already bite this Animal (it becomes also a Vampire) :) but maybe I should add some text to show the player, that he has successfully biten some Animal.