I am not expert in regards with transactions but I think they have some kind of minimum deposit and also with withdrawal. Before, I experienced this on 1xbit since they have minimum deposit before but the contact said I just need to fulfill the remaining of the minimum deposit to reflect it on my balance.
It really depends on the rules of each Casino, unfortunately this is the fault of the player and the Casino cannot be blamed, it is in the Bitstarz FAQ.
So OP has lost the money, it will never credited.
That's why it's important to read the FAQ at the Casino, especially if it's the first time playing and making a deposit otherwise something like this will happen.
Yeah, imho OP should have been more careful.
It's not the casino's fault that they have listed the minimum deposit amount clearly and OP chose to ignore it actively.
But at the same time, perhaps some negotiations with the casino support could get your balance credited? It's just that moving around small amounts of ETH is probably just not feasible for them financially.