Gameplay Color, developed by Jason Morley, is a JavaScript Game Boy Color emulator for iOS, based on the GameBoy-Online emulator core that installs as a web clip and allows you to play ROM games through your browser just as any other emulator app.
Instructions Gameplay Color requires two apps from the App Store to work, Google Drive (where your ROMs will go) and iDownloader (to extract the ROMs from the zip files).
Once you have those two apps, you want to head to the Gameplay website (gameplaycolor.com) and tap "Play Now."
The way you use this to play games is by "Adding To Homescreen" and getting a web clip that you can use to launch the emulator. Once it is open, you will be required to sign in to your Google Drive (Google account required) so you can select some games to play.
For a detailed video on how to do all this, watch it above!