The user interface or the front-end can be run on any server, while making calls to the back-end. When talking about a Casino DApp, this means that the front-end can be developed like any other app. However, the backend, or the internal workings of a casino are ran on a decentralized network. So payouts, the random number generator, the algorithms of the slots, etc – all of these are coded within the contracts which run on the network.
Since the technology is still somewhat in its infancy, and it takes time to develop an entire casino, the offerings are somewhat limited at the moment. Most of the available casino DApps are bare-bones dice bots and simple games where you can wager on a 50/50 situation. Although big leaps are being made by developers like FunFair, Edgeless, and others, for now we mostly have to make do with some fun but simple games like Etheroll.
It’s obviously not all gloom and doom, there are some great operators that offer their casino DApp at the moment while always improving. Also the rise of many new tokens that make application development much easier will pave the way for fantastic new casinos that can truly revolutionize the gambling business.