How to install a DLC or Add-On for 3rd party games?

[Zero Enna]

Hi, i installed a couple gog games through steam using destkop mode and they also work (control ultimate, empire earth) but i can't install dlcs that try to find the game automatically (katana dlc for ghostrunner) and the add-on for empire earth, despite seemingly being installed in the right folder, doesn't work either. when i want to start it, it tells me that i need to install the basegame.

Is there a way to install and use DLCs and Add-Ons or does that only work for steam-games (for now)?

[Marlock]

did you install the DLCs individually as 3rd-party apps on Steam?

are they windows or linux-native versions?

If you're using only native linux versions of everything, they should just work together, and if they don't you should complain to GOG that their installer is messed up (but do keep asking here too, there is always something else someone can help you try to work around the issue)

If you mix linux native and windows versions, that's just not gonna work


And if you tried only windows versions of both the game and the DLC, keep reading:

Steam's compatibility layer for running windows apps on linux (SteamOS 3 is a version of linux) is called Proton

Proton kind of sandboxes each game in a separate fake windows environment, so by default each 3rd-party windows app you install via Steam is isolated from the rest

In this thread I explained the basic steps to add/run two things in the same sandbox (which is called a Proton prefix folder):
https://steamcommunity.com/app/1675200/discussions/0/3274688652644804064/#c5154941593360317929

Then the game and DLC should be able to see each other

[Zero Enna]

Originally posted by Marlock:

did you install the DLCs individually as 3rd-party apps on Steam?

are they windows or linux-native versions?

If you're using only native linux versions of everything, they should just work together, and if they don't you should complain to GOG that their installer is messed up (but do keep asking here too, there is always something else someone can help you try to work around the issue)

If you mix linux native and windows versions, that's just not gonna work


And if you tried only windows versions of both the game and the DLC, keep reading:

Steam's compatibility layer for running windows apps on linux (SteamOS 3 is a version of linux) is called Proton

Proton kind of sandboxes each game in a separate fake windows environment, so by default each 3rd-party windows app you install via Steam is isolated from the rest

In this thread I explained the basic steps to add/run two things in the same sandbox (which is called a Proton prefix folder):
https://steamcommunity.com/app/1675200/discussions/0/3274688652644804064/#c5154941593360317929

Then the game and DLC should be able to see each other

sorry for the late answer, i had to wait for a usb-c stick so i could repair my steam os installation after the update killed it.

i tried doing that but it doesn't work for me. i tried to add the STEAM_COMPAT_DATA_PATH thing in all 3 lines (target, location, command) but nothing worked :-/ can you send a screenshot of where and how exactly you do that, especially since i don't have the %command% part?

€: got help, it works now xD i thought i had to replace/remove the %command% part because i don't have a command :D
was able to install the ghostrunner dlc. with empire earth i still have a problem though. it's empire earth gold so i installed basegame and add-on at the same time and it's in the same folder (same app id). still, when i try to launch the add-on, it tells me to install the basegame first