That was under Firefox 56.0 on Windows 10. I just tried with Chrome and it runs there, feedback later.
Interesting, the error was on the part that displays just a cover image on Chrome. I downloaded the Windows version and played it. I moved around with the snake and was wondering that touching yourself or the wall has no consequences. I got the feeding part, but the other progress bar I did not understand. I think I have not yet discovered everything, for example, how is the "leave a mark" topic addressed?