Mods are not being isolated into their own sandboxed assemblies

[valkyrienyanko]

Description

Mods with identical script names cause errors. This affects both C# and surprisingly GDScript mods too. This needs to be confirmed that this is happening on GDScript mods again.

Steps to Reproduce

1. Duplicate the res://Mods/Example Mod directory to res://Mods/Example Mod 2.
2. Modify the id in the mod.json of the new mod from example_mod to example_mod_2.
3. Run the game.

Expected Behavior

Both mods should load and execute without errors, printing unique messages.

Actual Behavior

C# Mods

• First Kind of Error:

  An item with the same key has already been added. Key: res://valkyrienyanko/example_mod/Mod.cs
  

  • Points to: ModLoader.cs#L74

• Second Kind of Error:

  Assembly with same name is already loaded
  

  • Points to: ModLoader.cs#L73

GDScript Mods

• Console Output:

  Loading C:/Users/VALK-DESKTOP/Documents/_Godot Projects/Template/GodotProject/Mods/Example Mod/mod.pck for example_mod
  Loading C:/Users/VALK-DESKTOP/Documents/_Godot Projects/Template/GodotProject/Mods/example_mod_2/mod.pck for example_mod_2
  Hello from Mod 1
  Hello from Mod 1
  

  • Expected: Hello from Mod 1 and Hello from Mod 2
  • Actual: Hello from Mod 1 printed twice

Observations

• C# scripts with the same name in different mods cause errors.
• GDScript mods with the same script names also have unexpected behavior. (needs to be looked into again)

Additional Notes

• Changing DLL names did not resolve the issue.
• Test files provided:
  • Example Mod.zip
  • example_mod_2.zip

Relevant Issues

• Godot 4 .Net - Loading / Assigning a script exported from another project fails with error ("Cannot instance script because the associated class could not be found") godotengine/godot#75352

Conclusion

• C# modding inside the Godot engine looks like a dead end.
• C# modding how rimworld did it might be an option. (There's https://github.com/Carnagion/Modot but as of writing this it's still on Godot 3.x)
• GDScript modding in the Godot engine might be an option. (The issue described above needs to be confirmed again)
• Lua modding might be an option.
• C++ modding?

What about security concerns? How can we limit modders to only modding the game and not my System32.dll?