Valve is not abandoning Windows or x86, but makes both optional — what does this mean for games?

Valve is moving forward with SteamOS, Proton, and FEX to make Windows and x86 optional in gaming, with Arm64EC; understand what this changes for gamers.

Valve is not abandoning Windows or x86, but it is making both less mandatory for running the Steam library. Software updates focus on compatibility and hardware responsiveness, with improvements that go beyond raw performance.

SteamOS evolves beyond the Deck

SteamOS has been preparing to work on more devices. Recent versions expand support, including the Legion Go S and other handhelds with NVMe, and update the compatibility system beyond the original Deck experience. In versions 3.7.8 and 3.8, the platform gained initial support for Steam Machines and an updated Arch base, unveiling an experience that is less "deck-bound."

Furthermore, Valve is preparing SteamOS to run on its own hardware in the future: the Steam Machine remains x86, and the Steam Frame VR uses the Snapdragon 8 Gen 3 (Arm64), which means that SteamOS and its compatibility stack already cover both x86 and Arm. The ecosystem is being designed to reduce single-platform dependencies.

Arm on the board: FEX-2604 and the Arm64EC leap

What has actually changed is the integration of FEX-2604 into Proton 11.0 Beta, along with an Arm64EC configuration. FEX is an x86 to Arm64 Linux emulator/JIT; it translates x86 instructions at runtime, while the Windows API and graphics components continue to be managed by Wine, DXVK, and VKD3D-Proton. This dual stack — FEX + Proton — separates instruction translation from Windows compatibility, reducing the weight of each layer.

This integration is the first to officially sit on the Proton beta stack, paving the way to run Windows x86-64 games on Arm hardware without requiring native Arm versions of every game.

Proton: the driving force behind compatibility

Proton remains the key piece that made Windows an option, not a requirement. The goal is to reduce dependency on Microsoft and Windows APIs, keeping the game stable behind a continuous compatibility layer.

The Deck helped create a feedback loop between developers and consumers: when games ran well on the Deck, there was an incentive for compatibility, which in turn increased interest in publishing with SteamOS and Proton. With this evolution, Windows may continue as a build target, but not as a mandatory runtime.

Among recent news, the integration of NTSYNC into the mainline kernel facilitates synchronization between Windows and Proton, and Wine 11.5's syscall user dispatch support helps with direct syscall cases, opening room for more games on the Arm64EC stack.

Performance in numbers and practical experience

The author's tests showed that, on high-performance ARM hardware, games like Cyberpunk 2077, Doom Eternal, and Counter-Strike 2 can run with good fluidity using FEX + Proton, even with the typical emulation overhead. In tests conducted on specific hardware, CS2 reached about 117 FPS at 1440p with maximum settings, Cyberpunk was close to 50 FPS, and Doom Eternal was between 140 and 170 FPS, demonstrating that the experience is already very close to native in many cases.

A key concept in this scenario is thunking: translated OpenGL/Vulkan calls are passed to native ARM libraries instead of the entire emulation stack, reducing CPU cost. When this is not possible, software rendering may occur, as happened in one of the initial test attempts.

What remains and what lies ahead

The ecosystem is not free of obstacles. Today, the biggest bottlenecks tend to be kernel-level anti-cheat, DRM, and platform services, in addition to code or timing particularities that still carry x86 assumptions. Valve cannot solve all of this alone.

Furthermore, the industry is already migrating to Arm: Microsoft is working with Prism on Windows 11 for x86-Arm translation, and Apple has already completed much of the transition with Rosetta 2. In this dance, Valve appears as a major Linux player, seeking to reduce dependence on Windows and x86 without completely abandoning the current ecosystem.

Conclusion: moving towards an increasingly system-independent library

With Proton and FEX matured, many games become invisible to the user — you can simply play, without thinking about the compatibility layer behind it. The developer community gains compatibility data via the Deck, and Valve seems to bet that, when hardware migrates from x86 to Arm without notice, the merit will continue to be that of what was built by the company.

And you? What is your bet: will you keep your library on Windows, or are you already rooting for an ecosystem where SteamOS, Proton, and FEX make Windows optional for your gaming experience? Leave your comment below and join the conversation.

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