Force the legacy OpenGL renderer (Unity games, legacy builds)
Effect
Windows only. Selects Unity's LEGACY OpenGL backend, not the core profile — use -force-glcore for that. Builds made with newer Unity versions may not carry the legacy backend at all, in which case this has no 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
Safe
PROTON_NO_D3D11=1 %command%Copy
Disable d3d11.dll (Linux, Proton)
Effect
For d3d11 games that can fall back to d3d9 and run better that way.
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.
