Hey - I'm the dev here.

You are given a hash, and you can decide whether you want to guess above/below your number.

So you are in complete control over whether the number you are above to be given is a winning one or not.

EDIT: For example, if the number you are given is 20, then it could be a winning number if you say 'below 50' or 'below 30' but it would also be a losing number if you say 'above 21' or 'above 90'.

Even if we were malicious, and the 20 wasn't fully random, you as the player always have complete control (via above/below and choosing a number) whether the 20 (or whatever the number is) is a winner or a loser.