Well, curacao-egaming.com are the ones who give the licenses from Costa Rica, they verify the engine and the site isn't rigged before giving the license.
That's not the case. Like the name suggests the licenses (Actually sub-licenses) are from Curacao, not Costa Rica. (Costa Rica is a popular place to incorporate a casino though, because it effectively has no gambling laws for foreign bets).
And they do
not verify the engine (and if they did, it could silently changed, or they verify a different version).
As someone who's previously been granted a gaming license, I can tell you they're pretty much totally useless for a player. I think the
only thing they're good for is showing that the company isn't a "fly-by-night" operation as they invested a few thousand in legal and licensing costs.
And if you're cheated by them, it gives you a potential avenue for recourse but it'd be a a pretty up-hill battle. And if they're malicious, they could've even gone through the whole licensing process with totally fake information and be anonymous.
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So my strong advice for players would be to use a system they can verify themselves (i.e. provably fair) and a long history of being good standing with the community (as that's something worth millions of dollars, no well-run company would want to risk that). I'd also check out:
https://cryptogambling.org/ while I don't know every name in the list, the ones I do know are pretty solid options.
Yes, with decentralization there is no check & balance and no central authority who could monitor all the fair plays and other stuff in gambling.
Rather i would say that this is much more better than a regulatory authority.
In case of Central gambling body, there might be some check and balance but more often we see these bodies are purchased by the big whales in the industry and they influence even those authorities to take biased decisions.
Now the only way for gambling site to survive for a long term is to be fair and supportive to its customers. Healthy competition among the sites is also benefit to the gamblers and i think gambling survival is best in the decentralized environment.