I played this website back when it first came out. It's a very fun game and unique

good to see it's still legit and running. I bet there's probably a lot of people and bots on it now-a-days so it must be like fighting in an arena for money LOL
It's not a matter of "sites fairness rating", as you wrote, but you may just verify by yourself if a bet was manipulated or not.
And with hundreds if not thousands that can do this, I really doubt that the admin(s) would even try to rig it once. They don't need to. They have an edge already.