SteamOS Launchers

How Zaparoo Core starts games on SteamOS. Install and reader setup are on the SteamOS page. For a launcher that isn't listed here, write a custom launcher.

Steam

Launches games from your Steam library via the steam:// URL scheme. Both official Steam games and non-Steam shortcuts added to your library are detected.

Zaparoo also tracks when you start Steam games externally (from Big Picture or the desktop client), showing the currently running game in ActiveMedia.

Core uses the configured install_dir or the first Steam installation it finds, normally ~/.steam/steam/ or ~/.local/share/Steam/. It indexes installed games from that installation and any additional libraries listed in Steam's libraryfolders.vdf, plus non-Steam shortcuts from Steam's user data.

To manually launch a Steam game, write steam://<app_id> to a token. For example: steam://1145360 for Hades.

config.toml

[[launchers.default]]
launcher = "Steam"
install_dir = "/custom/steam/path"  # Optional custom Steam install directory

Native emulators

Core does not install or configure native emulators for you.

Core can launch games directly through supported emulator Flatpaks and executables without routing them through EmuDeck or RetroDECK. It checks each runtime before selecting the launcher and reports missing emulators as unavailable.

Emulator	Systems	Detected runtime
Xenia Canary	Xbox 360	XeniaCanary executable
Ryubing	Nintendo Switch	io.github.ryubing.Ryujinx Flatpak
shadPS4	PlayStation 4	net.shadps4.shadPS4 Flatpak
PCSX2	PlayStation 2	net.pcsx2.PCSX2 Flatpak
Cemu	Wii U	info.cemu.Cemu Flatpak
Azahar	Nintendo 3DS	org.azahar_emu.Azahar Flatpak
Vita3K	PlayStation Vita	Vita3K executable
RPCS3	PlayStation 3	net.rpcs3.RPCS3 Flatpak
DuckStation	PlayStation	org.duckstation.DuckStation Flatpak
PPSSPP	PSP	org.ppsspp.PPSSPP Flatpak
Dolphin	GameCube and Wii	org.DolphinEmu.dolphin-emu Flatpak
melonDS	Nintendo DS	net.kuribo64.melonDS Flatpak
ScummVM	ScummVM	org.scummvm.ScummVM Flatpak
Supermodel	Sega Model 3	com.supermodel3.Supermodel Flatpak
xemu	Xbox	app.xemu.xemu Flatpak
MAME	Arcade	org.mamedev.MAME Flatpak
Flycast	Dreamcast, NAOMI, and Atomiswave	org.flycast.Flycast Flatpak
RMG	Nintendo 64	com.github.Rosalie241.RMG Flatpak
mGBA	Game Boy, Game Boy Color, and GBA	io.mgba.mGBA Flatpak
Ruffle	Flash (.swf)	rs.ruffle.Ruffle Flatpak
PrimeHack	GameCube and Wii	io.github.shiiion.primehack Flatpak

Each emulator is detected as a native executable on PATH or in ~/.local/bin, as an AppImage in ~/Applications, or as a Flatpak. Native filesystem scanning uses ES-DE-style system folders under the configured media roots, with ~/ROMs as the SteamOS default. Some launchers reuse compatible media indexed by another launcher instead of scanning the same files again.

shadPS4, Vita3K, and RPCS3 use .ps4, .psvita, and .ps3 pointer files respectively when scanning. Each file holds one launch target, up to 4096 bytes. ScummVM uses .scummvm target files. The launcher IDs, file types, and scanned folder for every emulator are listed under standalone emulators on the Linux launchers page; SteamOS uses the same detection.

Use launchers.preference to choose an ordered fallback between native emulators, EmuDeck, and RetroDECK:

config.toml

[launchers]
preference = ["Native", "EmuDeck", "RetroDECK"]

Core skips unavailable launchers in this preference list. Explicit token launchers, saved per-media overrides, and system defaults still take priority.

RetroArch

Core registers its supported RetroArch launchers and checks for the org.libretro.RetroArch Flatpak and each matching core file before launch. Launchers with a missing Flatpak or core remain visible as unavailable but are not selected for launches.

Games are indexed from ES-DE-style system folders under the configured media roots. Built-in controls include save state, load state, menu, pause, reset, fast forward, rewind, and stop.

Core uses Zaparoo-owned per-system configuration overlays, leaving your primary RetroArch configuration unchanged. These profiles enable network commands and low-latency settings while disabling threaded video, run-ahead, rewind, shaders, overlays, and automatic overrides for launches managed by Core.

In Gaming Mode, RetroArch launches use Zaparoo Runtime when it is available. Direct fallback launches use gamescope focus handling. You can override the core selected for a launcher with load_path.

EmuDeck

Zaparoo detects EmuDeck installations and creates launchers for supported system folders present in the EmuDeck ROM directory. RetroArch-based systems use Core's built-in RetroArch launchers, while other systems launch through standalone Flatpak emulators such as Dolphin and PCSX2. Missing emulators are reported as unavailable instead of being selected for a launch.

EmuDeck systems are available when the EmuDeck launcher wrapper for the emulator exists under tools/launchers next to the ROM directory, or when the matching emulator Flatpak is installed. If you moved the ROM directory, Core reads the new location from romsPath in ~/.config/EmuDeck/settings.sh.

Default paths:

• ROMs: ~/Emulation/roms/
• Gamelists: ~/ES-DE/gamelists/

Supported systems include: NES, SNES, Game Boy, GBA, N64, NDS, GameCube, Wii, Wii U, Switch, 3DS, Genesis, Saturn, Dreamcast, PSX, PS2, PS3, PSP, Neo Geo, Arcade, and many more.

Games are discovered using ES-DE's gamelist.xml files for proper display names.

RetroDECK

Zaparoo detects RetroDECK and creates launchers for recognized system folders in its ROM directory. Games launch through RetroDECK's unified CLI, which handles emulator selection internally.

RetroDECK is detected when the net.retrodeck.retrodeck Flatpak is installed and ~/retrodeck/roms/ exists. If you moved RetroDECK, Core reads the new locations from paths.rd_home_path and paths.roms_path in ~/.var/app/net.retrodeck.retrodeck/config/retrodeck/retrodeck.json.

Default paths:

• ROMs: ~/retrodeck/roms/
• Gamelists: ~/retrodeck/ES-DE/gamelists/

RetroDECK supports any system folder that matches an ES-DE system definition.

Bottles, Faugus, and Moonlight

Programs from Bottles, games from Faugus Launcher, and streamed apps through Moonlight are indexed and launched the same way as on desktop Linux. In Gaming Mode they use gamescope focus handling like other non-Steam launchers.

Kodi

Launch media content from a Kodi instance running on your network.

Supported content:

• Video and audio files
• Movies and TV episodes
• Music (songs, albums, artists)

config.toml

[[launchers.default]]
launcher = "Kodi"
server_url = "http://kodi:8080"

Replace kodi:8080 with your Kodi instance's address and web interface port.

Zaparoo Runtime and Gaming Mode

When Zaparoo Runtime is available, native emulators, RetroArch, EmuDeck, and RetroDECK run through one permanent Zaparoo Runtime non-Steam shortcut in Gaming Mode. The shortcut starts the requested emulator as a Steam-owned child process.

Core continues to show and track the requested game, not Zaparoo Runtime. Play history starts after the emulator launches and ends when it exits. Launching another token stops the current Runtime session before starting the replacement.

Zaparoo Runtime does not create per-game Steam shortcuts or modify Steam game pages. The installer adds default artwork for the permanent shortcut without replacing artwork you have customized. In Desktop Mode, or when Runtime is unavailable, Core falls back to direct launching.

Shell scripts

Execute allow-listed .sh files directly. Each file must be executable and use a valid shebang, such as #!/bin/bash.

System ID	Extensions
Any	.sh

config.toml

[launchers]
allow_file = [
    "^/home/deck/scripts/.*\\.sh$"
]