Proton Experimental fixes Crysis, CEG games, adds early 32bit OpenXR support

Valve's testing branch of Proton fixes Crysis and CEG-protected games on newer AMD chips and adds early 32-bit OpenXR support, gated behind an environment variable.

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Valve has pushed a new build of Proton Experimental, the testing branch of its Windows compatibility layer for SteamOS and desktop Linux, with fixes for two long-running headaches and a first step toward 32-bit virtual reality support. The changes are listed in the GitHub changelog and summarised by a GamingOnLinux report.

The headline fix undoes a regression that had made games using CEG, Valve's own Custom Executable Generation copy-protection scheme baked into some Steam builds, simply refuse to run under Proton Experimental. The changelog also lists a fix for Crysis and Crysis Wars, which had stopped working on newer AMD CPUs that support CPUID faulting, a security feature that lets an operating system mask certain processor capabilities from an application when it queries the CPU. The changelog does not say what the game was tripping over, only that it plays again.

Why CEG breakage matters more than it sounds

CEG protected games are a small but stubborn category. They are not always the newest or biggest titles, and the protection scheme has a habit of quietly tripping up compatibility layers that are otherwise fine with everything else in a user's library. A commenter under the GamingOnLinux report described trying to get Sniper Elite V2 working through repeated Proton updates, saying cracked copies run but with in-game bugs, and that this update was the first time the legitimate Steam version worked for them on Experimental. That is one person's account, not a guarantee it fixes every CEG title, but it matches the shape of the regression Valve describes fixing.

Crysis landing in the same update is a bit of a period piece. The 2007 shooter has long been a byword for hardware demands, and now it is some newer AMD processors with CPUID faulting support, not graphics cards, tripping it up. Old games breaking on new hardware in ways nobody planned for is exactly the kind of thing a compatibility layer ends up absorbing.

32-bit OpenXR is the interesting long game

The more forward-looking line in the changelog is early support for 32-bit OpenXR, the open standard that lets applications talk to VR and AR headsets without writing separate code for every device. Most modern software is 64-bit, but a fair number of older Windows games, including VR titles, were built as 32-bit executables, and OpenXR support for them has been missing under Proton until now. The catch is that it requires setting PROTON_USE_WOW64=1 on x86 systems, invoking WOW64, the layer that lets 32-bit Windows programs run inside a 64-bit environment. Valve has not said which headsets or titles this has been tested against, and the changelog does not promise it works reliably yet, only that support exists.

Smaller fixes round out the build: rendering corruption in Return to Krondor, garbled Japanese text in Killer7, and an error that appeared when quitting Hide and Moo! The GitHub changelog also notes this build carries over all changes from the numbered Proton 11.0-2 release, plus a long tail of earlier Experimental fixes covering everything from Far Cry to Kingdom Come: Deliverance II, and updates to Wine Mono and Xalia, the tool Proton uses to let a gamepad drive launcher and menu windows.

What is still unclear

Valve has not published performance figures for the OpenXR change, and there is no word yet on when, or whether, these fixes will graduate from Experimental into a numbered Proton release. Anyone wanting to try any of it can grab Proton Experimental through their Steam Library, though as ever with the Experimental branch, stability elsewhere in a given game's compatibility is not guaranteed just because one specific bug got squashed.

Sources

Image: Image: Crysis on Steam