Mortal Shell 2 on Steam Deck: Best Setup
Valve rates Mortal Shell II Playable on Deck — and with the right configuration it runs a stable 30 FPS in combat. Copy-paste settings below, tested on test build 24597645 (2026-08-13) with proton-11.0-2RC.
Recommended settings
| Setting | Recommended value | Notes |
|---|---|---|
| Proton | proton-11.0-2RC | No forced compatibility tool needed |
| Launch options | SteamDeck=0 %command% | Unlocks graphics settings (optional — playable by default) |
| Graphics preset | High | Locked by default; needs SteamDeck=0 |
| Upscaling | TSR | Better than FSR (the default upscaler) |
| Global Illumination | Medium | Needs unlocked menu; Low looks bad, Medium is the compromise |
| Frame Generation | Off | Main crash cause |
| Ray Tracing | Off | Too expensive |
| FPS cap | 30 | Stable 30 FPS in combat |
| Display mode | Fullscreen | Borderless hangs on death while streaming |
| Battery profiles | 40 FPS cap (LCD) / 45 FPS cap (OLED) | worldeka.com tested on both models |
| External controller | Quick Access Menu manual switch | Not auto-detected |
What to expect
Mortal Shell II runs around a locked 30 FPS in combat with occasional hitches, playable without any changes out of the box. Power draw sits at 12W-18W, the APU around 65°C-75°C, and battery life lands at roughly 2.5-3 hours.
“Surprisingly playable. Not ideal for a full playthrough, but satisfactory if it's your only option.” — Steam Deck HQ review
Frame Generation is the main crash trigger on PC and stays off on Deck. The developer-locked default preset is already sensible; unlocking the menu only matters if you want to tune Global Illumination or upscaling.
Unlocking the graphics menu (optional)
The graphics menu is locked by default on Deck. To unlock it, add SteamDeck=0 %command% to the game's launch options in Steam (Properties → General → Launch Options). This does not affect performance by itself — it just exposes the settings.
The one tweak worth making after unlocking: Global Illumination is locked to Low by default, which takes a big lighting toll. GI Medium improves dungeon visuals noticeably but adds visible haze/pixelation — it's a taste call. And whichever you choose, switch the upscaler from the default to TSR, which looks better than FSR on Deck.
Known Deck issues
- Occasionally shows non-Deck controller icons instead of the Deck layout.
- Some text runs small and is hard to read at 800p.
- External Bluetooth/USB controllers are not auto-detected — switch manually via the Quick Access Menu.
- Moonlight streaming: Borderless Windowed hangs after death when streaming to a Deck. Switch the game to Fullscreen.
- Proton specifics: D3D12 GPU crashes are reported under Proton (the
-dx11fallback causes visual glitches on Linux/Proton); RTX 5070 + Proton has an open white-texture-flickering bug (Proton GitHub issue #9993).
