* Run programs, scripts and AppImages from the desktop Windows programs open with the Proton Steam has chosen, and a Steam game's own launch program is handed to Steam. x86-64 Linux programs and game scripts run under FEX, and an exec the kernel refuses goes to droiddeck-open through libblsession's binfmt.c. Programs on noexec shared storage pass KIO's checks; a folder of Linux programs there, and sharun AppImages, are added by the app once and run from the copy. Executable scripts run without KIO's prompt, mpv plays on the software desktop, FEXServer's socket moves under XDG_RUNTIME_DIR, and Proton runtimes no longer show up as games. * Switch to Desktop from Big Picture without Deck mode Big Picture's Switch to Desktop asks the client's SteamOS manager, which the client only has when started as SteamOS (Deck mode). Without it the request failed and the screen stayed on "Switching to Desktop..." for good. The live compat helper now sees the request on its way to the client and hands it to steamos-session-select, which opens the KDE desktop as Deck mode already did. * Run x86 programs from shared storage where they lie FEX asks for the guest's PROT_EXEC when it maps a program or library, which the kernel refuses on noexec shared storage; FEX never runs those pages itself, so libblsession maps them without it in FEX's processes. An x86 game, its libraries and its start script now run in place instead of being copied in; only native code on noexec storage is still copied. A Steam library's games are never copied, and a Linux game's launch program opened from the desktop goes to Steam like a Windows one.
DroidDeck brings the SteamOS experience to Android: Valve's Steam client in Big Picture on your Adreno handheld, with Windows games through Valve's ARM64 Proton.
Note: DroidDeck does not have a stand-alone website. Do not click on any download links from websites claiming to be the DroidDeck team.
Requirements and install
Use Android 9 or newer on a supported Adreno device (730 or newer, or 8xx). Adreno 6xx is experimental: DirectX 11 uses DXVK 2 and may run, and DirectX 12 games can still crash. Mali, Xclipse, PowerVR, and Adreno 710 are unsupported. No root is required. Allow about 3 GB for the runtime and 1.1 GB more for the desktop and emulators. Install the APK from Releases, install the Linux runtime, then press Play and sign in. Steam downloads on first launch. Install Desktop & apps to use the desktop and emulators. The Store installs Linux apps and games from Flathub (ARM64 builds) with Flatpak; with additional options to install Appimages and set up scripts. Stores (Setup › Stores › "Show Stores in the rail") signs in to GOG, Epic Games and Amazon Games, browses their catalogs and libraries, downloads games into the Games storage and adds each one to the Steam client as a non-Steam game, so it launches through Proton like everything else; the cog on its chip row sets which tab a store opens on and the download speed tier.
Before Steam launches, you must turn off Restrict child processes in Developer options. If this option is not available in developer settings (Android 12 and 13 devices), first launch of Steam will present a "Fix it for me" button, which will help automate the setup process.
Community
Join the DroidDeck Discord for help, Preview builds, and device reports. Bug reports go in its #bug-reports forum; attach the zip from Share logs (Setup, or the session drawer) so the logs come with it.
Build
Run tools/build_local.sh with Docker, Java 17, the Android SDK/NDK, Rust through rustup, GitHub CLI, Python 3, and zstd installed. It prepares the same native libraries, pinned components and audio sinks as CI, then checks the APK's assets, JNI exports and dependencies. The APK is at app/build/outputs/apk/release/app-release.apk. Set DROIDDECK_PA13_SOURCE_DIR to an existing PulseAudio 13.0 source directory to skip downloading it. Set DROIDDECK_SIGNING_ENV to a signing environment file to install over a release build; relative keystore paths resolve beside that file. To install on an attached device, run tools/deploy_local.sh.
After preparation, ordinary ./gradlew :app:assembleRelease builds can reuse the verified inputs. If native sources, component pins or staged files change, packaging stops with instructions to rerun the helper. Generated audio stays under app/build/; the tracked base bundle is never modified. ./gradlew -PskipRust=true :app:testDebugUnitTest needs no native preparation. For an APK without store engines, use DROIDDECK_SKIP_RUST=1 tools/build_local.sh; it omits cached engine libraries too.
Run the helper and preload regression suite with bash tools/test_local.sh. On macOS it runs in Linux through Docker, matching the helpers' runtime and CI instead of compiling Linux preloads against macOS headers.
Limits
Compatibility and performance vary by device; hardware validation is limited. Desktop compositing uses software rendering. Firefox sandboxing is reduced under proot. Logs are kept app-private (files/logs/, the last 30 sessions); Share logs packs the newest session, with the stores and tool logs, into one scrubbed zip.
Credits and licence
GPL-3.0. Runtime, shim, input, and controller work build on WinNative and Bannerlator (maxjivi05). LSFG frame generation is from the work of Camille LaVey and the Eden emulator project, following lsfg-vk, ported to WinNative and DroidDeck by @maxjivi05; it needs your own copy of Lossless Scaling and ships none of its shaders. x86 AppImages, and any whose own runtime cannot unpack them, are unpacked with uruntime by VHSgunzo (MIT), shipped unmodified with its licence. See LICENSE. Steam and Proton belong to Valve Corporation; this project is not affiliated with Valve.
