The casino generated the winner themselves, meaning in theory they could know if the game Satoshi created would be a win for whoever joined, or a loss.
The casino could also generate their own name under a different pseudonym, and create one in which is a win for themselves while still providing the hash in the beginning.
This is the primary reason why we dont see any PvP game that comes popular because of this matter.House itself can possibly make an account to battle up with their users.
Theres no way on how to verify or detect if players are part of the house or not.We have seen several pvp gambling sites in the past but as usual they do end up dying or no players at all. Coinflip or any related or similar games doesnt really attract too much players.