Yeah I can't confirm the process for music since I haven't tried that yet. I may update this or throw a new one out when I do.

Thought I could get the remaster/Hulshult's music working by just throwing in extras.wad into the config but that didn't work. Guess I'll need to manually add the music in myself somehow

That's weird, did you happen to have Ultimate Doom installed before the DOOM + DOOM II update?

Either way, glad to hear you got it working!

I got it working!

I figured this problem was perhaps caused by GZDOOM not detecting other games besides The Ultimate Doom for some reason. I copied files DOOM.WAD and DOOM2.WAD to my dosbox folder and after launching DOOM + DOOM II via steam in DOS mode I immediately saw GZDOOM's launcher where I could select which game to run. I didn't get these launcher before. I also checked I had all relevant settings in game and in .ini file so that menu should've appeared (queryiwad=true).

Still weird why it required this extra step for me.

In GZDoom when you run it in DOS mode through Steam, when you go to the Options tab, do you have "Don't ask me again" checked? It sounds like you do.
Because when you run the game through Steam in DOS mode, GZDoom will always ask you which GAME/WAD you want to load

Okay I tried again with exactly the same files.

Maybe I don't understand how this is supposed to work. I tried launching the game (DOOM + DOOM 2) from Steam in DOS mode and it seems after step 8 I no longer get the menu where I can select which game to run. The menu I'm talking about is kind of DOS interface where you must choose from options between 1 to 7 first being The Ultimate doom and last is Quit.

So how do I select if I want to run Ultimate Doom or Doom 2?

Also in step 7 when I'm copying files from GZDOOM .zip file to dosbox folder there's one file which already exists in the said folder. I think it was libsndfile-1.dll. Are you supposed to replace the original file with the new file in GZDOOM .zip file? I chose to replace with new file.

I would recommend not installing the test versions and stick with the stable versions of both the mod and source as a first step in troubleshooting. I just tried again and the guide continues to work flawlessly when doing that. I haven't go through the process of trying test versions of the source/mod because of bugs.

Additionally, try to edit the ini file as laid out in the guide. Any additional edits you make, I can't speak to as I haven't tested.

I used to have this setup and working with separate installations of Ultimate Doom and Doom 2. I now followed this guide for new DOOM + DOOM 2. I removed all existing installations of the games and GZDOOM.

I got it kind of working but when running DOOM + DOOM 2 from steam it goes straight to Ultimate Doom. Before I edited the .ini file running the game in DOS mode went into menu where I could select which Doom to run but now it just goes straight to Ultimate Doom.

I followed the guide exactly but instead Project Brutality I downloaded Brutal Doom v22 test 4. So downloaded different mod files and also edited the .ini file with lines Path=brutalv22test4.pk3.

What am I doing wrong? How do I get the menu where I select the game?

Jadiz, yes that's correct Step 8 has you doing that, deleting dosbox then renaming gzdoom to dosbox.
After you do the fresh install of both the source and the mod and generated the .ini config file and edited that, you launched it through Steam?

You should have gotten the option after that to launch the "Doom + Doom II" version or the "DOS version". You want to launch the DOS version in order for GZDoom to launch (a.k.a. the renamed dosbox.exe) then your mods you have enabled in the .ini file should load up without any issues.

i did have to tinker but it does work