There's a problem with your provably fair method (you copied the bustabit scheme, without doing the "seeding event" to prove that the hash chain itself is fair). In other words: you are proving the games are predetermined, but you're not proving they're from a fair distribution. Does this qualify for the 100 ETH bounty?
Can you clarify what specific game you are referring because the original games of Bitcasino is usually just from game providers that customized a game exclusive for Bitcasino. I’m trying to browse what game you are referring but can’t find what game in this casino that needs seeding event.
Also can you provide their bug bounty program so that we can verify the terms of the said event. All you can do is just conclude that the result is predetermined without giving an actual evidence for their game potential problem.