Roobet allow users to play with funds from deposits while those deposits are still unconfirmed. However, before you can withdraw any winnings, your deposit must confirm to avoid people double spending and leaving the casino out of pocket.
I'm just amazed they allow zero-deposit transactions with such a low fee. Unless it's tied to OP's (high level) account, this could easily be abused ("deposit 1 Bitcoin at low fee, go all-in, double spend if lost").