Ubisoft has set September 10 as the day For Honor stops working on SteamOS, Steam Deck, Steam Machine and desktop Linux, and the mechanism is a setting rather than a technical wall. In the same window, a back-end change in Warhammer 40,000: Space Marine 2 started crashing the game under Proton Experimental, and Valve's August survey put Linux back below four percent of Steam users.
For Honor loses its Linux anti-cheat on September 10
For Honor runs Easy Anti-Cheat with Linux support currently enabled, and that is what Ubisoft is turning off, which takes the game off every SteamOS and Linux device at once, as GamingOnLinux reports from Ubisoft's announcement. The published wording is that the team "cannot meaningfully deploy protection on this platform" and that reopening it later is a possibility rather than a commitment.
That phrasing is worth reading carefully. EAC's Proton mode is something a developer switches on or off, so what changed is Ubisoft's confidence in detection under Proton, not a capability that stopped existing. No detection or cheat-prevalence numbers were published alongside the decision, so the size of the problem it solves is not something an outside observer can check.
For Honor joins a list that already includes the Battlefield series, Apex Legends and GTA V. The shape of it is consistent: competitive multiplayer titles leave, while single-player and co-op games keep running. For anyone whose Deck library leans on live-service shooters and fighters, that is a standing risk to plan around rather than a one-off, and it is the one category of breakage that no Proton update can fix.
Space Marine 2 crashes under Proton Experimental
Space Marine 2 began crashing on SteamOS, Steam Machine and desktop Linux without any announced game patch, which points at a back-end change interacting with Easy Anti-Cheat rather than shipped code. Players report the crash clears when the compatibility tool is changed: Proton 9 works for some, Proton 11 for others, and Valve has the title set to Proton Experimental by default, which is why so many people hit it at the same time. Those are user reports from a Steam forum thread and a Proton bug report, collected by GamingOnLinux, not a diagnosis confirmed by Valve or Saber Interactive, and it may resolve itself in the next Experimental build.
The practical habit this rewards is knowing where the per-game compatibility override lives in Steam's properties menu before something breaks. Pinning a numbered Proton release is the safer state for any anti-cheat gated game, because Experimental changes under you and an EAC handshake is exactly the kind of thing that notices.
Linux share back under four percent in August
Valve's August 2026 Hardware and Software Survey puts Linux at 3.90 percent, down 0.11 points, with Windows at 93.95 percent and macOS at 2.14 percent, per GamingOnLinux's breakdown. Linux had crossed four percent in July and reached a record 5.33 percent in March, and has been moving inside a three-to-four percent band since, as Phoronix notes on the August result.
The survey measures share, not headcount, and the denominator moves. Simplified Chinese gained 1.45 points to 23.97 percent in the same month, a swing that has repeatedly lined up with Linux's percentage falling while nothing changed on the Linux side. Absolute Linux numbers could be flat or higher; Valve does not publish them, so the honest reading of a 0.11 point dip is that it is noise until several months point the same way.
The distribution split is the more useful part of the data. SteamOS Holo still leads at 21.07 percent but gave up 1.17 points, while CachyOS gained 1.16 points to 15.47 percent, with Arch, Linux Mint 22.3 and Bazzite following in the 7 to 9 percent range. Valve's hardware anchors the platform, but a substantial and growing share of Linux gaming is people who picked a desktop distribution deliberately, which is a different audience from someone who bought a Deck and never left game mode. For either, the check worth doing before buying a live-service title is its current anti-cheat status on Linux rather than its Verified badge, because Verified describes how the game runs today and says nothing about whether the publisher will leave the Linux switch on.