Roulette is using Bitcoin Lightning Network for Deposits and Withdrawals. In order to Spin the Wheel you need to deposit some satoshis to your onsite balance over lightning first. You can deposit as low as 1 satoshi to start with. All withdrawals are instant.
Lightning Roulette uses a provably fair system that allows players to check the integrity of every spin and confirm they have not been manipulated. It's also open source