Valve has released an update for Proton Experimental, the testing ground for compatibility improvements on Linux, SteamOS, and Steam Deck. The August 19, 2026, release focuses on resolving specific input and UI bugs for several strategy and open-world titles.
Key Game Fixes
Players experiencing technical hurdles in the following titles can now use the updated Proton Experimental build to resolve these issues:
- Company of Heroes 3: Fixed an issue where the middle mouse button failed to move the camera.
- Avatar: Frontiers of Pandora: Resolved a bug where the game failed to detect game controllers.
- Arma 3: Fixed input issues that occurred when switching focus between the game window and the launcher while running in gamescope.
Additional Improvements
The update also addresses broader compatibility concerns for the following games:
- Horizon Zero Dawn Remastered & The Last of Us Part II: Fixed a display bug where the Gnome top bar appeared in fullscreen mode.
- The Unfinished Swan: Fixed a lock-up that occurred after opening the in-game book.
- The I of the Dragon: Fixed a non-interactable mouse cursor in the main menu.
- Command & Conquer: Generals: Resolved graphical glitches in the menu caused by a previous Proton 11 regression.
Additionally, the update includes fixes for CEG-using games, which should now launch without the extra startup delay introduced in recent versions. Elisa: The Innkeeper - Prequel has also been restored to a playable state following a previous experimental regression.
New Playable Titles
The latest Proton Experimental update marks the following titles as now playable on Linux and SteamOS:
- City Car Driving
- Korea. IL-2 Series
- The Heroic Legend of America: Second Revolutionary War