Valve has released another update for Proton Experimental, bringing several compatibility fixes for Windows games running through Steam on Linux and SteamOS.
The September 4 update is particularly useful for Steam Deck and other Linux gaming users, as it addresses problems affecting games including Far Cry 4 and Grand Theft Auto III.
While this isn’t a massive Proton release packed with headline features, the update continues Valve’s steady work on improving compatibility across the huge Windows game library available through Steam.
Among the notable fixes, Far Cry 4 now has more reliable controller support, while an issue affecting the introductory videos in Grand Theft Auto III has also been resolved.
Far Cry 4 Gets a Controller Fix
One of the more notable changes in the latest Proton Experimental build concerns Far Cry 4.
Valve has fixed an issue that caused the controller to work unreliably in the game.
That’s particularly relevant for Steam Deck players, where controller input is fundamental to the experience.
Far Cry 4 is an older Ubisoft open-world shooter, but improvements like this show why Proton compatibility work remains important. A game doesn’t necessarily need to be a brand-new release to benefit from Valve’s ongoing development.
For players who already own Far Cry 4 on Steam and prefer playing it through SteamOS, the fix should make the experience more dependable.
GTA 3 Intro Videos Are Working Again
The update also addresses a regression affecting Grand Theft Auto III.
According to the Proton Experimental changelog, the game’s intro videos now play again after being affected by a Proton 11 regression.
This is a relatively small fix, but it illustrates an important aspect of compatibility layers.
A game can work correctly for years and then suddenly encounter problems after another component of the software stack changes.
That’s why Proton development isn’t simply about adding support for new games. Valve also has to make sure older titles don’t break as the compatibility layer evolves.
Several Proton 11 Regressions Have Been Fixed
The GTA 3 fix is part of a broader group of Proton 11 regression fixes included in the latest Experimental update.
Valve also addressed problems affecting several other games.
RaceRoom Racing Experience should once again load its HUD during races, while Lunacid: Tears of the Moon and Ligo are playable again after their respective issues were fixed.
These aren’t necessarily games that will generate the same amount of attention as Far Cry 4 or GTA 3, but they are exactly the type of compatibility problems Proton Experimental is designed to catch before changes make their way into a stable Proton release.
Cool People Club Is Now Playable
The update also adds Cool People Club to the list of games that are now playable through Proton Experimental.
That’s another important part of Proton’s development.
Valve’s compatibility layer isn’t limited to fixing older games. Experimental builds are also used to test compatibility with games that previously couldn’t run correctly.
For Linux and SteamOS users, that gradually expands the number of Windows games that can be played without requiring a separate Windows installation.
What Exactly Is Proton Experimental?
For players unfamiliar with Proton, it is essentially Valve’s testing ground for compatibility improvements.
Proton allows Windows games to run on Linux through the Steam client. It is based on technologies including Wine and incorporates additional components designed specifically for gaming. Steam Deck uses Proton to run many Windows games despite the device running SteamOS rather than Windows.
The Experimental branch receives changes before they are necessarily incorporated into stable numbered Proton releases.
That makes it useful for players who want to test the latest compatibility improvements, but it also means Experimental isn’t necessarily the version everyone should use.
If a game is already working perfectly on a stable Proton release, there may be little reason to switch simply because a new Experimental build has arrived.
For users experiencing a specific compatibility problem, however, Experimental can be worth trying.
Why These Small Updates Matter for Steam Deck
It is easy to overlook compatibility fixes because they don’t necessarily change graphics or add major gameplay features.
For Steam Deck owners, though, these updates can make a meaningful difference.
The device relies heavily on Proton because a large portion of the Steam library was originally designed for Windows.
Every compatibility improvement therefore has the potential to make another game more usable on SteamOS.
Valve’s approach also means that improvements aren’t necessarily restricted to the newest hardware.
A fix for an older game such as Far Cry 4 or GTA 3 can benefit someone playing on a current Steam Deck just as much as someone using another Linux gaming PC.
Proton’s Compatibility Work Is Ongoing
The latest update follows a pattern that Steam Deck and Linux gaming users have become accustomed to.
Valve continuously updates Proton with fixes for individual games, regressions and compatibility problems.
The previous Proton Experimental update arrived on August 28, while another update before that was released on August 19.
That regular development cycle is one of the reasons Proton has become such an important part of PC gaming on Linux.
Rather than treating compatibility as a finished problem, Valve continues adjusting the technology as games, drivers and other components change.
That also explains why a game that worked yesterday can occasionally experience a problem after a Proton update.
The trade-off is that fixes for one title or system can sometimes introduce regressions elsewhere.
How to Install Proton Experimental
Steam users can find Proton versions directly through their Steam Library.
To use Proton Experimental, players can select the compatibility tool from a game’s properties and choose the Experimental version.
However, there is an important reason not to blindly switch every game to Experimental.
It is a testing branch.
If your games already work properly, sticking with a stable Proton version is generally the safer choice. Experimental is most useful when you want to test a recent compatibility fix or need a newer change that hasn’t reached the stable release yet.
What the Update Means for Steam Deck Players
For Steam Deck owners, the biggest practical improvements in this update are straightforward.
Far Cry 4 gets more reliable controller functionality.
Grand Theft Auto III gets its introductory videos working again.
Other games receive fixes for specific problems, while Cool People Club becomes playable through Proton Experimental.
None of these changes fundamentally transform Steam Deck gaming.
But that’s not really the purpose of a Proton Experimental update.
The strength of Proton comes from hundreds of small improvements accumulating over time.
Final Thoughts
Valve’s latest Proton Experimental update may not be the biggest release of the year, but it delivers several useful compatibility improvements for Linux and SteamOS gamers.
The most recognizable fixes include Far Cry 4’s controller reliability and Grand Theft Auto III’s returning intro videos, while RaceRoom Racing Experience, Lunacid: Tears of the Moon and Ligo also receive fixes for Proton 11 regressions.
The update also makes Cool People Club playable.
For Steam Deck users, the bigger story is the continued development of Proton itself.
Valve is still actively working through compatibility issues across an enormous Windows game library, helping older games remain playable while adding support for newer ones.
It’s not flashy.
But for Linux gaming, this kind of maintenance is exactly what keeps the ecosystem moving forward.
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