I assume you already have this app, and I also assume you have already downloaded the Pokémon ruby zip file but when you open it it doesn't work. That is because pokemon ruby was not played on this app "My oldboy" it is played on a app by the same creates of this one called "My boy." This is a great website https://www.loveroms.com/roms.php?q=Pokemon it's where I downloaded my pokemon roms. Beside each pokemon game name is a type of console, Gameboy advance is for the "My boy" app while the Gameboy color is for this app "My oldboy," I hope this review helps you out. And good luck