This is a good good development I must say, I tried checking the site out, but unfortunately, it's not loading for me, I don't know what could be the reason but that by the way..

Games, be it lottery or gambling games, built on-chain are decentralized quite alright, and win or loss is determined by the smart contract as stated by the op, but my major concern here is trust, how can players really trust that the smart contract is not rigged/rugged, i.e written with some malicious code in it to ensure that the game favors the owners the most, and favor the user a little, just so the users don't suspect fowl play?

This I believe is something you guys will have to really assure the community of, else, many are just gonna be skeptical.