I've gone ahead and read into your provably fair methodology.
There's a problem here which immediately stands out to me, you're not using an external source of randomness to pull the results.
Ontop of an external random source, it needs to be unknown untill both players are in the match as well, and verifiable beforehand that it wasn't changed.
Like I said earlier this can be accomplished by either using random.org's ticket API OR using something such as the hash of an unmined bitcoin block.
The reason you generating a random winner and hashing it with a salt beforehand and displaying the hash to the user, isn't random, is due to the fact the house could know who wins in this case.
Ontop of the house being able to know who the winner or loser is, they can purposely make games under their own accounts as well in which are wins for them and still seem "provably fair"