Double or Nothing is a gambling dApp built on the Ropsten Test Network. It uses a pseudo-random number generator in its smart contract to generate a number that is either 0 or 1. If the number is 0, then the user loses his/her money. If the number is 1, then the user double's his/her money. The amount of money that is able to be gambled must be less than the money locked inside the pool. This project was built using Alchemy's hosted nodes and the template from their tutorial : https://www.alchemy.com/ .
You can see the code for the smart contract here : https://ropsten.etherscan.io/address/0x801e0d41690455451afF0d37fE57331ed98d9eBf#code