Turns off in-process esync primitives. Worth trying for games that hang or crash under Proton.
Proton-Deck
Valve ProtonAdded Jul 8, 2026Last checked Sep 13, 2026Also documented for this game on ProtonDB · checked Nov 9, 2026
Safe
PROTON_NO_FSYNC=1 %command%Copy
Do not use futex-based in-process synchronization primitives
Proton-Deck
ProtonDBAdded Jul 11, 2026Last checked Sep 27, 2026Also documented for this game on ProtonDB · checked Nov 9, 2026
Safe
PROTON_NO_NTSYNC=1 %command%Copy
Do not use the ntsync kernel module for in-process synchronization primitives
Proton-Deck
ProtonDBAdded Nov 13, 2026Last checked Nov 13, 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 24, 2026Also documented for this game on ProtonDB · checked Nov 9, 2026
Safe
mangohud %command%Copy
Show the MangoHud performance overlay (Linux)
Effect
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 24, 2026Also documented for this game on ProtonDB · checked Nov 9, 2026
Safe
PROTON_FORCE_LARGE_ADDRESS_AWARE=1 %command%Copy
Force the LARGE_ADDRESS_AWARE flag (Linux, Proton)
Effect
Lets 32-bit executables address more than 2 GB. Valve documents it as enabled by default, so setting it explicitly is usually a no-op.
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.
