I have made a remake of flappy bird on a website, but right now a friend of mine has found a way to cheat and easily get a very high score. The problem is that the client sends a request to the webserver each time the bird goes through the pipes then the webserver processes that and keeps track of your score, this means that a person who knows javascript can easily look at my code and change it to send requests without playing. I know that there is no way to prevent people from changing client side code, but I was just wondering if there even is a way to prevent this type of cheating. I know that the only way would be server side validation and authentication, but how can I do that with such a simple game?

So far I have just obfuscated the client code and I have put a ratelimit on the endpoint that keeps track of the score.