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Launching Flatpak Games & Apps with RetroDECK

Flatpak logo

This experiment was initiated by the users murkl and Daeymon. Then later expanded upon by the RetroDECK Team. The goal was to explore the possibility of launching external desktop games and apps within RetroDECK.

Note: RetroDECK was never intended to be used in this manner, so things like inputs may work as expected.

Disclaimer on Experiments

These experiments are created by the RetroDECK Team and/or Community. The guides are intended for people with technical knowledge and a passion for tinkering. Using these guides might put RetroDECK and your data at risk. The RetroDECK Team can't provide any support for these experiments or fix any issues they might cause on your system or RetroDECK installation.

Prerequisites

Flatpak Spawn Permission

Information:

This experiment requires the flatpak-spawn permission, which breaks the sandbox environment that RetroDECK operates in. Therefore, we do not recommend attempting this unless you are confident in your understanding of the process and its implications.

You can enable it by running this command in the terminal.

flatpak override --user --talk-name=org.freedesktop.Flatpak net.retrodeck.retrodeck

Add RetroDECK to Steam

We also recommend that you add RetroDECK to Steam to utilize Steam Input as there is a higher chance of inputs working from the external source.

Also some RetroDECK built-in hotkeys in the radials like Alt+F4 might help you close windows.

Directory structure

Type Folder Comment
Desktop Roms Folder retrodeck/roms/desktop/

How-to: Make .desktop files

Make an empty file with the <gamename>.desktop.

Example:

Ultima I.desktop and put it into the retrodeck/roms/desktop/ folder.

How-to: Launch Flatpak Games

You can either copy and edit the desktop files or make your own.

Tips on Applications with Launchers:

If the application has a launcher and you don't want to boot into it.

When editing the Exec= in the .desktop files, check the applications documentation if there is a way to launch it without the launcher via cli.

Add that to the Exec= command.

Example: Steam uses -silent and Heroic --no-gui.

Step 1: Find the files

Note: All files here are symlinks, but the export folders contains them all in a conventient way.

Depending if you how you have installed the application they can either be under:

  • System Wide: /var/lib/flatpak/exports/share/applications/
  • Local User: ~/.local/share/flatpak/exports/share/applications/

Step 2: Show Target

Right Click on the symlinked .desktop file in the folder and press Show Target.

This will take you to the real .desktop shortcut.

Example eu.vcmi.VCMI.desktop:

  • System Wide: /var/lib/flatpak/app/eu.vcmi.VCMI/current/active/export/share/applications/
  • Local User: ~/.local/share/flatpak/app/eu.vcmi.VCMI/current/active/export/share/applications/

Step 3: Copy the .desktop file

Copy the .desktop file to retrodeck/roms/desktop/

Step 4: Rename the file

Rename the file to something more fitting.

Examples:

net.openra.OpenRA.desktop → OpenRA.desktop or Red Alert.desktop

eu.vcmi.VCMI.desktop → VCMI.desktop or Heroes of Might and Magic III.desktop

Step 5: Edit the file

Open the .desktop file and edit the Exec= values so they are changed to flatpak-spawn --host flatpak run.

Example VCMI.desktop:

  • Before: Exec=/usr/bin/flatpak run --branch=stable --arch=x86_64 --command=vcmilauncher eu.vcmi.VCMI
  • After: Exec=flatpak-spawn --host flatpak run --branch=stable --arch=x86_64 --command=vcmilauncher eu.vcmi.VCMI

Make your own desktop files

Step 1: Create an empty desktop file

First, create the .desktop file as mentioned above with the game name and put it in the retrodeck/roms/desktop/ folder.

Step 2: Get the Run Command and Full Flatpak Name.

Find them on Desktop

Note this was done in KDE

  • Right Click in on the Application in the Application Launcher Menu and press Edit Application.
  • Command-line arguments should contain the Full Flatpak Name and Run Command.

Find them on Flathub:

  • Go to Flathub.
  • On flathub go to a the application you want to add, press the Down Arrow next to Download Button to get the Run Command and Full Flatpak Name.

Example: OpenRA.desktop

OpenRA - Flathub

  • Run command: flatpak run net.openra.OpenRA
  • Full Flatpak Name: net.openra.OpenRA

Step 3: Populate the .desktop file

Open the .desktop file and populate it.

Copy this:

[Desktop Entry]
Type=Application
Name=NAMEHERE
Icon=FULLFLATPAKNAMEHERE
Exec=flatpak-spawn --host flatpak run RUNCOMMMANDHERE
Categories=Game

Change the values of:

  • Name= NAMEHERE
  • Icon= FULLFLATPAKNAMEHERE
  • Exec= RUNCOMMMANDHERE

Example: OpenRA.desktop

[Desktop Entry]
Type=Application
Name=OpenRA
Icon=net.openra.OpenRA
Exec=flatpak-spawn --host flatpak run net.openra.OpenRA
Categories=Game

The Last Step: Launch the Games via RetroDECK & Scrape

After the .desktop files have been created and everything is working as expected, RetroDECK will recognize the .desktop file the next time you start it.

The games will appear under the Windows tab in ES-DE. If you have named the games correctly, there is a good chance that the scraper will identify them.