Valve had not published a Steam Deck compatibility rating for Legacy Edition AppID 2523770 when checked on August 15, 2026: the compatibility endpoint returned category 0 with no test items. The Steam store lists Windows, not native Linux. Community reports can still help test Proton, but “launches for one player” is not the same as Valve Verified or official support.
Official status
No Valve Deck verdict or issue list is available; keep that unknown separate from player success reports.
Baseline test
Start with Steam's default Proton choice, no launch options, and a short Bree dialogue and combat run.
Reported symptom
A current guide reports severe FPS and audio stutter when NPC voice lines begin on Deck and Arch Linux.
Fallback scope
GE-Proton and environment options are unofficial workarounds; change one variable and preserve a clean rollback.
Begin from the unmodified Steam configuration
Install Legacy Edition to internal storage or a healthy library, let Steam complete prerequisites, and launch with the default compatibility selection. Do not paste several environment variables or install a custom Proton build before observing the actual problem.
In Bree, test menu text, controller prompts, camera, NPC dialogue, audio, and a short combat route. Record performance before and during voice lines. Suspend and resume once only after a normal save and exit path are understood.
Because Valve has no published result, every behavior is a local observation. Note Deck model, SteamOS channel, Proton version, resolution, frame cap, and date.
Isolate dialogue-triggered stutter
A current AppID 2523770 community guide reports that performance may remain above 60 FPS and then drop sharply with audio crackle or desynchronization as NPC dialogue begins. The author attributes it to Wine/Proton media-stream codec behavior and reports testing on EndeavourOS and Steam Deck.
Reproduce the symptom in the same conversation twice. Compare a combat scene without voice lines. If frame rate is low everywhere, graphics settings, storage, thermals, or power limits are more likely than the specific dialogue issue.
Capture Steam’s performance overlay and the exact dialogue trigger. A repeatable before/after trace is more useful than “Deck runs badly.”
Evaluate the community Proton workaround cautiously
The community guide proposes GE-Proton9-5 and optional launch variables WINE_DO_NOT_CREATE_STRMF=1 PROTON_NO_ESYNC=1 %command%. These are not Valve or Aspyr instructions and may age. Install custom Proton only from a trusted manager such as ProtonUp-Qt, record the version, and test GE-Proton alone before adding variables.
If the custom runtime fixes audio but breaks multiplayer, video, controls, or saving, revert through Properties → Compatibility to the prior known-working tool. Do not delete the prefix while the only campaign save is unverified.
Change one option at a time and repeat the same Bree dialogue. Keep screenshots of the working selection rather than relying on a version name remembered later.
Tune presentation after correctness
Once dialogue and input are stable, choose a frame cap that the device holds through crowded fights. Lower expensive graphics options gradually and retain readable text. The Windows requirement lists 60 GB storage and DirectX 11 hardware baselines, but it does not promise a Deck performance target.
The official store lists full controller support and gamepad recommendation, which supports a controller-first interface but does not replace Deck-specific verification. Test on-screen keyboard needs, glyphs, and menus directly.
For online co-op, run a short lobby and verify saving before a full chapter. Proton changes that solve audio could affect networking.
Report and recheck the status
Before applying this guide later, reopen the Steam Deck compatibility details. A future Valve rating and issue list should replace the category-0 statement. Keep any community workaround labeled with its tested runtime and date.
For persistent problems, send Aspyr the AppID, Deck model, SteamOS and Proton versions, exact trigger, and logs or video. See Controller Setup for input and System Requirements for the official Windows baseline.