Run in fullscreen mode (Unreal Engine and Source games)
Effect
Overrides a saved windowed preference. -full is the same option in Source.
Display
UniversalAdded Jun 27, 2026Last checked Sep 12, 2026
Safe
-dx11Copy
Use the DirectX 11 renderer (Unreal Engine games)
Effect
Selects DX11 as the RHI. Ignored by builds without a DX11 path.
Display
UniversalAdded Jun 27, 2026Last checked Sep 9, 2026
Safe
-highCopy
Run the game at High process priority (Source engine games)
Effect
Raises the OS scheduling priority of the game process. It does not add CPU capacity, so it helps only where something else is competing for the processor.
Performance
UniversalAdded Jun 27, 2026Last checked Sep 9, 2026
Safe
-windowedCopy
Run in windowed mode (Unreal Engine and Source games)
Effect
Unreal documents pairing it with an explicit resolution. In Source -window, -sw and -startwindowed are the same option.
Draws FPS, frame timing and CPU/GPU load over Vulkan and OpenGL games. MangoHud runs the game, so %command% is what it runs.
Proton-Deck
MangoHudAdded Jun 29, 2026Last checked Sep 12, 2026
Safe
gamemoderun %command%Copy
Run the game under Feral GameMode (Linux)
Effect
Applies temporary host optimisations (CPU governor, I/O and process priority) for the game's lifetime, then restores them on exit. GameMode runs the game, so %command% is what it runs.
Proton-Deck
Feral GameModeAdded Jun 29, 2026Last checked Sep 12, 2026
On the General tab, find the Launch Options field.
Type or paste the option (e.g. -windowed) into the field. To use several at once, separate them with spaces (e.g. -windowed -novid).
Close Properties. Steam saves automatically, and the option applies next time you launch the game.
To remove one, reopen the same field and delete the text. Options are game-specific; an option that helps one game may do nothing (or misbehave) in another.
Worth knowing: a launch option can break a game's rendering, reset local settings, or trip anti-cheat in multiplayer. Read the description first, add one at a time, and treat anything rated above Safe as a deliberate experiment.
