Example Flatpak manifest for a Godot game using Godot's tutorial game

com.ssokolow.DodgeTheCreeps.desktop

[Desktop Entry]
Version=1.0
Type=Application

Name=Dodge The Creeps
Categories=Game;ArcadeGame;

Icon=com.ssokolow.DodgeTheCreeps
Exec=godot-runner
Terminal=false

com.ssokolow.DodgeTheCreeps.json

{
    "app-id": "com.ssokolow.DodgeTheCreeps",
    "runtime": "org.freedesktop.Platform",
    "runtime-version": "19.08",
    "base": "org.godotengine.godot.BaseApp",
    "base-version": "3.2",
    "sdk": "org.freedesktop.Sdk",
    "command": "godot-runner",
    "modules": [
        {
            "name": "dodge_the_creeps",
            "buildsystem": "simple",
            "build-commands": [
                "install -D game.pck /app/bin/godot-runner.pck",
                "install -D LICENSE.txt /app/bin/LICENSE.txt",
                "install -D com.ssokolow.DodgeTheCreeps.png /app/share/icons/hicolor/128x128/apps/com.ssokolow.DodgeTheCreeps.png",
                "install -D com.ssokolow.DodgeTheCreeps.desktop /app/share/applications/com.ssokolow.DodgeTheCreeps.desktop",
                "install -D com.ssokolow.DodgeTheCreeps.metainfo.xml /app/share/metainfo/com.ssokolow.DodgeTheCreeps.metainfo.xml"
            ],
            "sources": [
                {
                    "type": "file",
                    "path": "game.pck"
                },
                {
                    "type": "file",
                    "path": "LICENSE.txt"
                },
                {
                    "type": "file",
                    "path": "com.ssokolow.DodgeTheCreeps.png"
                },
                {
                    "type": "file",
                    "path": "com.ssokolow.DodgeTheCreeps.desktop"
                },
                {
                    "type": "file",
                    "path": "com.ssokolow.DodgeTheCreeps.metainfo.xml"
                }
            ]
        }
    ],
    "finish-args": [
        "--share=ipc",
        "--socket=x11",
        "--socket=pulseaudio",
        "--device=dri"
    ]
}

com.ssokolow.DodgeTheCreeps.metainfo.xml

<?xml version="1.0"?>
<!-- TODO: Look into how best to generate this programmatically

See
- https://www.freedesktop.org/software/appstream/metainfocreator/
- https://www.freedesktop.org/software/appstream/docs/chap-Quickstart.html
- https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html
-->
<component type="desktop-application">
  <!-- NOTE: If creating a new application in a post-Ubuntu 16.04 LTS world,
    the .desktop at the end is unnecessary. -->
  <id>com.ssokolow.DodgeTheCreeps.desktop</id>
  <name>Tweaked "Dodge the Creeps" example</name>
  <summary>Godot's tutorial project, with an annoying delay removed and
    simultaneous support for keyboard and mouse/touch input that allows
    drag-based mouse/touch input</summary>
  <categories>
    <category>Game</category>
    <category>ArcadeGame</category>
  </categories>
  <launchable>
    <desktop-id>com.ssokolow.DodgeTheCreeps</desktop-id>
  </launchable>
  <requires>
    <control>pointing</control>
    <control>keyboard</control>
    <control>touch</control>
  </requires>
  <project_license>MIT</project_license>
  <developer_name>Stephan Sokolow and the Godot Team</developer_name>
  <!-- Not supporrted in the Ubuntu 16.04 LTS version of appstream-util -->
  <!--<url type="contact">http://blog.ssokolow.com/contact/</url>-->
  <metadata_license>CC0-1.0</metadata_license>
  <!-- See https://hughsie.github.io/oars/generate.html -->
  <content_rating type="oars-1.0"/>
</component>