Can't launching Sonic Generations (2011) with any mod on Steam Deck (Proton)

[LotharieSlayer]

Hello,

I'm a bit desperate because I love to play/speedrun on Unleashed Project for Sonic Generations. Since few weeks now, I can't play Sonic Generations (2011) anymore when it has mods on my Steam Deck, the game just don't want to launch and crash few seconds after clicking on play. (Still working like a charm on my Windows PC)

The only mod that work as far as i know is Direct3D 11, Sonic Generations runs well on Steam Deck through HedgeModManager. But at the instant I'm adding Unleashed Project and Unleashed Project Low End or only with Jet Set Generations to the config, and then I launch Sonic Generations, the game start (with the right GraphicsConfig.cfg) and then crash, but don't know why because I never changed the config since months.

Both SonicGMI and HedgeModManager goes to the same result when I'm adding more than just Direct3D 11 with any version of Proton. (already tried with Proton Experimental, 10.0 (beta) and 8.0) the game just won't run. And I'm also wondering if this problem does not come from a Steam Deck Update (currently on 3.7.13).

I don't know where to search for help on that issue, so I'm asking here because you might know something at hedge-dev to fix it or to redirect me to the right team or the right person to talk with.

Context (Environment)

• SteamOS version: 3.7.13 (20250630.1)
• Linux Kernel: 6.11.11-valve19-1-neptune-611-g88b36d49a5e3
• HedgeModManager 8.0.0-beta4

Placing here some files that might helps you to understand, both of them just end by pid 50192 != 50190, skipping destruction (fork without exec?) for example :

• (proton-10beta)-steam-71340.log
• (proton-experimental)-steam-71340.log
• HedgeModManager.log

I tried to log the Debug Console from HedgeModManager, but don't found where the outputs are, let me know their locations in order to give you them.

Thank you for your amazing work! 😄

[thesupersonic16]

I am not really sure what the issue is. Are you able to consistently get it to crash with other mods but not Direct3D 11? If you can, maybe try deleting the Codes.dll file from the mods directory then start the game directly. Don't use Hedge Mod Manager to save or start the game for this test as it will regenerate the file. Deleting this file should disable the CLR loader that is within the mod loader which some mods require.

In a seperate test could you also try using an older version of Proton?

[LotharieSlayer]

I continued to investigate and unfortunately deleting or keeping Codes.dll doesn't seems to changing anything... And older versions of Proton too.

But well I found a very weird workaround to get other mods working and it's maybe my fault due to all the previous tests, and perhaps through these steps, you will understand what is happening, because I have no idea.

Steps to reproduce

Enable mods for the first time (require SonicGMI and HedgeModManager)

• Go in SonicGMI
• Tick mods you want
• Tick Enable mods in CPKREDIR Options
• Click Save and then Install/Uninstall to enable mods
• Go in HedgeModManager
• Go in Settings
• Check if Mod Loader is On
  • If yes, click Uninstall but leave the Mod Loader parameter on On
  • If no, enable Mod Loader, restart HedgeModManager, go to Settings and click Uninstall but leave the Mod Loader on On
• Then it just works by never reopening HedgeModManager
• Launch Sonic Generations from Steam and it's working with mods (from SonicGMI).

Add new mods (require SonicGMI only)

• Go in Sonic GMI
• Tick new mods
• Click Save
• Launch Sonic Generations from Steam

Note : If I don't have HedgeModManager but only SonicGMI it's not working. And if I tick Off in HedgeModManager/Settings/Mod Loader it's not working too.

[thesupersonic16]

SonicGMI uses CPKREDIR, HMM uses HE1ML which is backwards compatible and designed to replace CPKREDIR. You will not beable to use codes or DLL mods without HE1ML.

Some other things you could try that might be useful to know:

• Try a popular Proton fork such as GE
• Try installing .NET Framework such as .NET Framework 4.8 on the game prefix.
• Checking paths in cpkredir.ini

I am not very sure if Sonic Generations (2011) has been tested on Linux since the release of HMM 8. Maybe it is having issues with Linux paths. You could try converting them to a Windows compatible path if it is not already. Z drive letter usually points to root.