Prevent AJAX cheating on a web game [duplicate]

Question

This question already has an answer here:

• Prevent Direct Access To File Called By ajax Function 12 answers

Context

I have a web game in JavaScript.

I send scores and achievements with AJAX during the game.

So anyone can view the source code, copy this request and cheat on my game.

Questions

• Any idea of how prevent this?
• With a token from server (I never used this system)?

Code

jquery:

$.post('ajax/score.php', {pseudo: $pseudo, score: $score, achiev: $achiev},
    function(data) {
        $('#loader').show().delay(3000).fadeOut(1000);
    }
);

php:

if (isset($_POST['pseudo']) &&
    isset($_POST['score']) && 
    isset($_POST['achiev'])) {
    ...
}

Answer 1

As the game is client side, there is no way to ensure that they do not "cheat". There are ways to make it more difficult.

• Have all calculations performed serverside, and send back tokens...this may not be possible/feasible for your game.
• Change the code served each time so that it will require more time to "decipher" all the requests.
• Obfuscate the code...this is only a deterrent.
• Have "tokens" sent during the game to see if the data matches (for example you can't win the racing game in 5 sec)...this too can be spoofed.

As long as the game is client side, it cannot be "secured".