A free program for Android, by Paul Willi.

Citro is a free and fast emulator for GameBoy 3DS and Advanced games. This is the best way to play your favorite games on the most popular Android devices, from very low-end phones to modern tablets.

It is based on the latest version of the 3DS hardware, and it is designed to be compatible with all GameBoy 3DS and Advanced games. It has an in-built link cable emulation, which allows you to connect your device to another device and play the game on the second device.

It supports all the games that you can play on your phones or tablets.

Citro can be controlled using external USB/Bluetooth controllers, keyboard, touchscreen or trackball.