How can you trust the official when you don't know anything about him as you know, once the transaction is signed, your money will be in unsafe hands and you can't get it back. If you like free spins, there are many casinos that offer them so search for them and enjoy playing for free, and do not try to think of such silly ideas because they will make you lose a lot of time in vain!!!
^ The only problem here is the trust of handling our money to admin. What if the admin will scam us and run away together with our money.
I don't know how to work this idea but I think it is good if you will create a gambling casino with a decentralized concept, through a smart contract, or in a blockchain network if you are using BTC. In that kind of concept that OP wants, it needs first to have a trust or entrust someone.
Nevertheless, good luck with your proposal.