In this tutorial you will learn how to create your own Highscores for your games, using your own free server / database. Let's go! Here's an example of how the...
Keep in mind: Nothing on the player's computer should be trusted. Your game is your enemies hands, it is compromised. The perfect anti-cheating system doesn't exist if you have a dedicated hacker in front of you.
** I suggest to "record" your games and send it to the server (the inputs) so you can "replay" the game and check if the score is good. You can save random_seeds, save every move (ex: chess game), then replay it later. **
The next option is a bit more risky. The hash key is "obfuscation", which means "confusion" but it's not really unhackeable 100%.
Maybe this helps for hash:
construct.net/en/forum/extending-construct-2/addons-29/plugincb-hash-md5-sha-1-sha-39765