[LaganYT]

Adds Browse, Start In, and Reset to the Compatibility panel. The picker writes ordinary shell launch options that replace the game executable while preserving the compatibility tool, arguments, prefix, and Steam identity.

No runtime launch changes. Tested through /bin/sh and /bin/dash, plus panel, routing, environment, and webpatch checks. Linux and Elden Ring with Mod Engine 2 have not been tested end to end.

[NotProtonNot]

I'd love to improve documentation, but documentation must be written by hand. Not necessarily by me personally, but by a human.

[NotProtonNot]

Does the way this functionality was implemented match how the same functionality works on Linux? The systems that Linux users use to launch arbitrary binaries inside a game's prefix (there are many different ways) should all work under NotProton with zero changes.

Please give a mod's 'here's how to run on Linux>' instructions a try. If they are not working under NotProton but do work under Linux, I'd want to know. High priority fix for issues like that.

[LaganYT]

Fair point on the docs, I'll drop the README change.

On Linux parity: I tried the usual Linux launch options for swapping the game's exe, bash -c 'exec "${@/eldenring.exe/launchmod_eldenring.bat}"' -- %command% and the echo "%command%" | sed ... | sh version. Both already work in NotProton without this PR. The .bat runs in the game's prefix with the Steam app ID.

The one catch is Mod Engine 2's .bat runs .\modengine2_launcher.exe, so it has to start from its own folder. Proton's steam.exe doesn't change folder for a .bat, so it starts in the game folder, and NotProton does the same. Unpacking ME2 into the game folder works. That matches Proton, so I don't think NotProton needs a change for this.

Since launch options already cover it, the Executable setting here would be a NotProton-only way of doing the same thing. I'll close this unless you think it's still worth having.

[NotProtonNot]

Fair point on the docs, I'll drop the README change.

On Linux parity: I tried the usual Linux launch options for swapping the game's exe, bash -c 'exec "${@/eldenring.exe/launchmod_eldenring.bat}"' -- %command% and the echo "%command%" | sed ... | sh version. Both already work in NotProton without this PR. The .bat runs in the game's prefix with the Steam app ID.

The one catch is Mod Engine 2's .bat runs .\modengine2_launcher.exe, so it has to start from its own folder. Proton's steam.exe doesn't change folder for a .bat, so it starts in the game folder, and NotProton does the same. Unpacking ME2 into the game folder works. That matches Proton, so I don't think NotProton needs a change for this.

Since launch options already cover it, the Executable setting here would be a NotProton-only way of doing the same thing. I'll close this unless you think it's still worth having.

Is there a UX benefit to your approach? Is there a way to offer that UX benefit to a user without altering how launches work (unless that altering is to match how things work under Proton)?

[LaganYT]

The benefit is the picker. Writing the right Linux one-liner, getting the bash quoting right, and knowing the game's exe name is the hard part for most people, and Reset puts it back.

I think the panel can keep that without changing launches. Instead of setting its own variable, Browse would write a normal Linux-style launch option, along the lines of cd '/path/to/ModEngine2' && bash -c 'exec "${@/*eldenring.exe//path/to/ModEngine2/launchmod_eldenring.bat}"' -- %command%. The cd is what makes Start In work. Proton doesn't change folder, so that matches Linux too. The run script would go back to how it is on main, and the launch option would work as-is in Steam on Linux.

If that sounds right I'll rework the PR that way.

[NotProtonNot]

The benefit is the picker. Writing the right Linux one-liner, getting the bash quoting right, and knowing the game's exe name is the hard part for most people, and Reset puts it back.

I think the panel can keep that without changing launches. Instead of setting its own variable, Browse would write a normal Linux-style launch option, along the lines of cd '/path/to/ModEngine2' && bash -c 'exec "${@/*eldenring.exe//path/to/ModEngine2/launchmod_eldenring.bat}"' -- %command%. The cd is what makes Start In work. Proton doesn't change folder, so that matches Linux too. The run script would go back to how it is on main, and the launch option would work as-is in Steam on Linux.

If that sounds right I'll rework the PR that way.

Now we're talking. Yeah, that's the way. I think that is worth doing & would be a fairly easy merge on my end.

The launch arguments system is complex, be warned. I have plans to make it less hellish, but it's currently fairly hell. Fair warning!

[LaganYT]

Reworked it that way. The picker now writes ordinary shell launch options, and the runtime script matches main. Browse, Start In, and Reset are still there.

The checks pass under /bin/sh and /bin/dash, including quoting, arguments, working directory, settings, and Steam identity. I haven’t tested it on Linux or with Elden Ring and Mod Engine 2 end to end as I do not own those games.

[NotProtonNot]

Will review and merge soon.

[NotProtonNot]

Forgot to do this. Up late for some reason, will actually do this maybe in the morning...