no cheat? if you are not cheating your players then can you show us your new provably fair system on how it works? and i wonder how could the hacker hack your site and provide winning hashes since it depends on the blockchain

It seems to me that you thought your players (or in general any bitcoin users that create a transaction) have no control on their TxID, which simply is not true. If you have no idea about my second sentence in my previous post, you'd better do some research on how the "createrawtransaction" and "signrawtransaction" APIs can be used to create a transaction without broadcasting it.