https://koditips.com/retro-games-kodi/

Kodi Retroarch

https://launchpad.net/~libretro/+archive/ubuntu/stable
https://launchpad.net/~libretro/+archive/ubuntu/testing

Install Retroarch on your device.

Next, we have some basic Retroarch setup to perform to enable external app launching.
How to set up Retroarch External App

  Launch the Retroarch app you installed above.
  Go to Online Updater
  Then, go to Core Updater
  Click on at least one core for every system you’d like to play to update it.

It is highly recommended that you update the:

  Core Info Files
  Assets
  Autoconfig Profiles
  Cheats
  Databases
  Overlays
  Shaders

How to Configure Retroarch Location in IAGL Kodi Addon

  Run Kodi and head into your video addons where the IAGL Kodi addon sites.
  Hover over top of it and long press or press the menu (‘c’ button) and then select Settings.
  Go into the External Launchers tab.
  Click on My System Type and select it from this list.
  You will have to complete all of the fields that now show up in order to get Retroarch to launch.

Here are some helpful hints about some of the options that you will see:

  Retroarch System Folder = It will be located at _//data/data/com.retroarch/ _for most users.
  Retroarch CFG Location = This is the “retroarch.cfg” file location, which stores a bunch of retroarch settings. It can be located in a number of locations including:
  Close Kodi on Launch = Some operating systems allow you to close Kodi when Retroarch is opened if you wish.
  Pause Kodi on Launch = Likewise, some operating systems pause Kodi when Retroarch is launched so that it doesn’t take up any resources.

How to Launch Retroarch From IAGL Kodi Addon

Once your external location is set up, we can force some retro games to launch via the external app.

  Launch the Internet Archive Game Launch Kodi addon
  Head into the Browse All Lists playlist
  Hover on the console you want to launch using Retroarch, such a Sega Dreamcast or Nintendo 64.
  Long press or press the menu button to bring open the context menu and then select Update Launch
  Change this from Kodi to External to use the external settings you setup above.