Install the right emulator and the right user interface to make your smartphone a real portable retrogaming console.
Emulators for old video game consoles are plentiful on the Google Play Store, but not all are created equal. Some support multiple platforms of the same brand, while others focus on a specific console, forcing users to multiply emulators on their device. However, there is a unique, powerful and very complete solution capable of emulating dozens of game consoles: RetroArch.
If informed users are probably already very familiar with this open source emulator which allows you to download the kernels of dozens of consoles, the application is not known for its interface. Not very intuitive, it is frankly not easy to master, making this emulator difficult to configure.
Developers, however, addressed this difficulty and ended up developing independent graphical interfaces, working in concert with RetroArch. Once installed, they allow you to take advantage of the power of RetroArch in a simplified environment, accessible to all.
1. Organize your ROMs
Before you start, you will need to organize the storage of your game ROMs on your Android smartphone. Create a general ROM directory, then in it, create as many subdirectories as you have systems to support.

2. Download RetroArch
Then download the open source RetroArch application. It is a powerful game console emulator allowing to emulate the cores of the majority of the consoles of yesteryear. It offers the ability to individually download the core of each console you want to use, so you can play all your old games across all platforms from a single app.
Only downside, as we said above, RetroArch is perfectly usable after installation but its interface is far from easy to master. Once the application is installed on your smartphone, do not open it and go directly to the next step.
Download RetroArch for Android (Free)
3. Download and set up Dig Emulator Front-End
While advanced users can easily accommodate RetroArch’s interface, others can use a third-party application for a more welcoming interface. This is what Dig Emulator Front-End offers, an independent interface that scans the content of your smartphone to organize and present your games by displaying, for example, the visuals of the various titles, and by organizing them by console. Note that Dig is not an emulator. In addition to offering a simple, clear, and concise interface, Dig is responsible for making the link with RetroArch by launching the right emulator according to the game selected.
Download DIG Emulator Front-End for Android (Free)
Once Dig is installed on your smartphone, open the app and accept the permissions requested by the app. Dig completes its installation and asks you if you want the app to search for game ROMs on your device. Press OK.

Once all the ROMs are found, Dig displays its home page which shows the total number of games, genres and systems represented. Enter Systems to browse your games by console, then choose one of the systems. The games are presented in the form of a grid showing the covers of each of the titles you own.

Touch the cover of a game to enter its description, and press the play button. As no emulator is currently installed in RetroArch, Dig is unable to launch the game. Instead, it displays an alert showing the name of the kernel to be installed in RetroArch. Remember the name of the component to download since Dig will not display a second alert and does not offer a direct link to the kernel download on RetroArch. Press OK.

If you want to use another emulator than the one natively suggested by Dig, you can check if it is compatible by consulting the list of compatible emulators uploaded by its developers.
4. Install RetroArch compatible cores
Dig does not work with all emulators offered by RetroArch. When you pressed OK in the previous step, DIG should automatically launch RetroArch. Accept the access permissions requested by the multi-emulator application by pressing OK, then Allow. RetroArch finalizes its installation and displays its home page.

To download the kernel required to launch your game, enter the Load Core menu, then the Download Core submenu… The list of all kernels available in RetroArch appears. Scroll through the cores offered to find the one you need to launch your game.

For better readability, turn your smartphone to landscape view to display the full names of the nuclei.
Be careful, a slap on a kernel instantly launches its download and installation. Scroll through them delicately and tap the kernel to install when you’ve found the right one.
RetroArch displays a faint yellow line at the bottom of the screen indicating the progress of the process.

Return to the home page by tapping the arrow at the top left of the window next to the Core Updater label. You can verify the correct installation of the emulator by returning to the Load Core menu where the emulator you just installed should appear.
You can then close RetroArch. Do not hesitate to kill RetroArch and Dig so that your changes are taken into account the next time you start these two applications.

5. Start a game from Dig
Open Dig again, then go back to System to launch the game you wanted to play. Dig then opens it automatically, thus avoiding the painful gymnastics imposed by RetroArch to play. Natively, the game controls are set to be displayed in landscape mode.

If you want to play in portrait mode, especially for portable consoles like the Game Boy, press the circular arrow button, displayed transparently, to get the controls in portrait mode.
Indeed, if the screen orientation in portrait or landscape is detected automatically when you rotate your smartphone, you will have to manually replace the control keys.

When you have finished your game, to turn off your virtual console, touch the RetroArch icon (represented by the icon of an alien from Space invaders), then touch the Close Content menu to close the game.
To return to the Dig interface, then press the arrow next to Quick Menu and select Quit RetroArch. You can do this more drastically by killant directly the application.

Note that you will have to repeat steps 4 and 5 each time you want to run a game from a new platform.
6. Update the list of games in Dig
If you plan to add new game ROMs as you go, you may need to ask DIG to manually scan your device’s memory if the app does not do this automatically on startup. To do this, from the DIG home page, enter Options, then in Games scan, press the OK button in front of the Start manual scan menu.

7. Display a shortcut to a game on the home page of your smartphone
If you play a particular title frequently, it is possible to avoid having to launch Dig each time by creating a shortcut directly on the home page of your smartphone.
Open Dig, enter the relevant game file, then expand the options by touching the button with three superimposed dots. Press Add to the home screen, select Shortcut, and validate your choice by tapping the Add Automatically button.

8. Save a game
Unlike older consoles, RetroArch allows you to save a game in progress. To do this, from your game, press the RetroArch button and touch the Save State menu. The game is then automatically saved in this state.
Note that it is possible to save several separate parts by choosing a different “slot” from the State Slot menu. The game will always be saved to the Slot selected in this menu.

To restart a saved game, relaunch the game, display the RetroArch menu, and press Load State. Your saved game is then automatically restarted where you left off. To return to the game, press Resume.