In this case, implementing KYC is the best option to avoid that abusers on your gambling site, they must be filled up the form before joining from your site. I don't have experience on this but technically most of the site now was implementing KYC, i don't know if some people like this but if your site was profitable to them they keep coming. Another thing that you can avoid is higher the amount they can withdraw not like the same amount on the faucet.
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1. Prevent sign ups from temporarily email domains
2. Block all VPNS/Tor/Sock5
3. Restrict accounts to 1 per IP address, but don't make this rule public knowledge otherwise it will be circumvented.
I would rather suggest the number 1 and 2.