r2modmanPlus VS MultiMC5

Had the same Issue and found the solution on the r2modman Discord. https://github.com/ebkr/r2modmanPlus/wiki/Modding-on-a-Steam-Deck-and-Linux

It looks like this is the same issue some r2modman users are having with Risk of Rain 2. Not sure if it's a Steam manifest issue, r2modman, or something else. The workaround listed in that issue report worked for me, but I had to make some modifications because r2mod is a script designed for RoR2. Here's what I did:

It worked out of the box for me on EndeavourOS, so long as I used the r2modman launcher. Have you tried the "Copy the profile from r2modman into the game directory" method detailed here? https://github.com/ebkr/r2modmanPlus/wiki/Modding-on-a-Steam-Deck Apparently you ignore those first pop-up instructions. My game didn't have the "linux_wrapper.sh" executable at all, so it wouldn't even run with that launch option, but the rest worked fine, at least on my machine.

Many more classes and items via mods. Mods more than double the content; safe and easy to install(R2modman).

I'm not familiar with Steam Deck but I do use r2modman on Nobara Linux to mod Valheim. You can find it on Github (https://github.com/ebkr/r2modmanPlus); it has an in-built browser for the mods from Thunderstore.

r2modman has Muck support.

Additionally, you could submit an issue on the github for that project: ttps://github.com/ebkr/r2modmanPlus/issues

Isn't thunderstore mod manager just a reskin of the open source r2modman?

Or download appropriate installer from https://github.com/ebkr/r2modmanPlus/releases

MultiMC How to Import Instances: https://github.com/MultiMC/MultiMC5/wiki/Import-Instance

MutliMC: https://multimc.org/

probably not with an unmodded version. if you want to use a different launcher for whatever reason i would recommend taking a look at MultiMC (https://multimc.org/) its a free multi platform launcher that lets you log in with both mojang and microsoft accounts and lets you have multiple installations of minecraft in the same launcher (very nice with modpacks so that you don’t have to keep messing around in the mods folder) its works on macos, linux and windows. so if you are using the old launcher because the new one doesn’t work on your current operating system this launcher might just work!

See some screenshots here: https://multimc.org/

I use Multi MC for addons and mods. https://multimc.org/ might make it easier.

Honestly Just get GDlauncher or MultiMC , both eliminate the need for the overwolf FTB hybrid. GDlauncher is pretty straight forward , I dont personally use MultiMC but alot of people do so theres bound to be guides on yt .

MultiMC is what you're looking for. It tries to retain compatibility with very old MC.