DR2 (Epic) fails with "Steam failed to initialize" (LAUNCHER_ERR_STEAM_FAILED) across all launch methods #5835 #964

🐞 Describe the Bug

Red Dead Redemption 2 (owned on Epic Games Store, not Steam) fails to launch with "Steam failed to initialize" (Rockstar Launcher error LAUNCHER_ERR_STEAM_FAILED), even after installing Epic Games Launcher + Rockstar Games Launcher via NSL into a shared Proton prefix as described in issue #869.

Which version are you using?

• NonSteamLaunchers.desktop (Desktop Version)

🔁 To Reproduce

Steps to reproduce the behavior:

1. Switch to Desktop Mode.
2. Launch NSL using the .desktop script.
3. Select and install Epic Games AND Rockstar Games Launcher together (shared prefix).
4. Set GE-Proton10-29 as compatibility tool on both Epic Games and Rockstar Games Launcher Steam shortcuts.
5. Add WINEDLLOVERRIDES="vulkan-1=n,b" %command% to Epic Games Launcher's Steam launch options.
6. Launch Epic Games Launcher, log in, install/launch Red Dead Redemption 2.
7. Rockstar Games Launcher starts automatically with correct Epic auth parameters (-epicAppId=rdr2, -AUTH_TYPE=exchangecode, -EpicPortal, etc.), then immediately fails.

I also reproduced the identical error via two other independent methods before trying NSL:

• Heroic Games Launcher (Flatpak) with USE_FAKE_EPIC_EXE=true environment variable
• Adding the Epic Games Launcher directly as a non-Steam Steam shortcut (no Heroic, no NSL)

All three methods fail at the exact same point with the exact same error.

✅ Expected Behavior

Red Dead Redemption 2 should launch normally through Rockstar Games Launcher after being started via the Epic Games path, without requiring the game to actually be owned/detected via Steam.

🖼️ Screenshots / Logs

Rockstar Games Launcher log (NSL attempt):
Main] [external] Creating Steam min mode launch
[Main] [external] Steam App Id: 4249992855
[Main] [external] Steam Location: C:\Program Files\Epic Games\RedDeadRedemption2
[Main] [metadatamanager] Read external Steam metadata: rdr2
[Main] [external] Steam not detected as parent process
[Main] [launcher] Passed check: majorVersion(10.0.19045) >= 10
[ ERROR ] [Main] [launcher] Steam is not initialized
[ ERROR ] [Main] [error] * Category: 1 (ERROR_CATEGORY_LAUNCHER)
[ ERROR ] [Main] [error] * Code: 113 (LAUNCHER_ERR_STEAM_FAILED)
[ ERROR ] [Main] [error] * Localised: Steam failed to initialize. Please verify that the Steam Client is running and try again.

Rockstar Games Launcher log (Heroic attempt, for comparison — same error, different generated Steam App Id):

[Main] [external] Creating Steam min mode launch
[Main] [external] Steam App Id: 1174180
[Main] [metadatamanager] Read external Steam metadata: rdr2
[Main] [external] Steam not detected as parent process
[ ERROR ] [Main] [launcher] Steam is not initialized
[ ERROR ] [Main] [error] * Code: 113 (LAUNCHER_ERR_STEAM_FAILED)

Steam itself is confirmed running and logged in during all attempts (desktop tray icon visible, overlay functional in other games).

🧰 System Information

Device Type

• Desktop PC (Steam Machine, not a Steam Deck)

Operating System

• SteamOS (Arch-based)

Details

• SteamOS Version: 3.8.16 holo
• Kernel Version: 6.16.12-valve24.5-1-neptune-616-gb2f7cfe85e45
• Proton Version Used: GE-Proton10-29 (also tried GE-Proton11-5 via Heroic)
• Launchers Affected: Epic Games (Rockstar Games Launcher, launching RDR2)
• NSL Version: v4.2.91
• Install Method: Script (.desktop)

💬 Additional Context

• Occurs only in Desktop Mode (also tried Game Mode with same result)
• Reinstalling NSL did not fix the issue
• Clearing compatibility data did not help
• I am using a custom Proton build

This appears to be a check inside RDR2/Rockstar Launcher itself that verifies Steam ownership/Steam-as-parent-process regardless of the Epic launch path, and it fails identically across Flatpak (Heroic), native Steam shortcut, and a fully separate NSL Proton prefix. Happy to provide additional logs or test further steps if anyone has ideas.