IF THERE ARE ANY ERRORS (which there probably is), let me know in guide comments below and I may investigate...

※The port currently DOES NOT support PK3 files.

※If using the steam launch parameters to load wads, these wads will be permanently loaded until you restart the game without the launch parameters.

※Note that 3rd party wads must be loaded via absolute path. Wads should be at most MBF21 compatible ( no fancy features from gzdoom etc. and no support for ZSCRIPT/DECORATE).

※Another note that a lot of wads may crash the game because it either contains advanced features or some other problem where it should work but doesn't. Working wads may randomly crash.

※Updated as of Monday, October 7, 2024
There are 3 ways you can load your wad(s).

• Launch parameters in steam,
  however, these wads will be permanently loaded until you relaunch the game without the parameters.
  
  
• "wad" console command. This command allows you to load multiple wads.
  
• Drag and drop to mod folder in the save game directory. This only loads a singular wad.

1. Right click DOOM + DOOM II and click Properties.

2. In the advanced section text box, put in:
-file "x1" "x2" etc
Where "x" is your list of PWADs. Each pwad has to be in its own quotations.

For example, if you had a wad called "mycoolmappack.wad" and "awesomeguns.wad" located in "C:\WADS" to be played in "Doom 2" and your steam folder is in the root of "C drive", you would put in, with quotation marks at the ends:

-file "C:\WADS\mycoolmappack.wad" "C:\WADS\awesomeguns.wad"


※Reminder if using the steam launch parameters to load wads, these wads will be permanently loaded until you restart the game without the launch parameters.

※Updated as of Thursday, October 3, 2024

1. Press the ~ key to bring up the console once a game has been launched.

2. Type in "wad" then add the path to your wad(s)
For example, if you want to run the wad "Eternal Doom III" but use weapons from "Vesper" which is named "eternall.wad" and "xa-vesper_1.0.0.wad" located in "C:\WADS", you would put in, with quotation marks at the ends:

wad "C:\WADS\eternall.wad, C:\WADS\xa-vesper_1.0.0.wad"

The game will automatically restart with the loaded wads.

※Updated as of Monday, October 7, 2024

1. Load into a game of your choice and then select the "Mods" section

2. Select "Play" then select to open the mods directory.

3. An external window will open. Here, you can paste your wads into this folder.

4. Once you are finished, back out of the "Play" menu and re-enter for your local wads to show up.

The game will automatically restart with the loaded wads and the appropriate IWAD

Wads used for this test and images:

Eternal Doom 3
https://www.doomworld.com/idgames/themes/TeamTNT/eternal/eternal

Vesper Weapon Mod
https://hellforgestudios.com/doomforge/vesper/

Bloodstain
https://www.doomworld.com/idgames/levels/doom2/Ports/megawads/bstain

1. When launching the game, choose an IWAD you would like to load your wad(s) in (Usually this will be Doom 1 or Doom 2)

2. Press the ~ key to bring up the console.

3. Type in d_pwads then press enter. This should show all the pwads that is currently loaded for your desired game.

※If the output shows nothing, no pwads are loaded. Otherwise, everything will be listed here.

3b. Alternatively, in addition, if you want to use a subscribed mod, load that up first. Then you can type in "d_pwads" in console to easily pull up the absolute path of that wad location. You will need this absolute path for the next steps.
※ Note that some "Featured" Mods may not display a path in the "d_pwads" but it is still loaded. In this case, you would only need to add your additional PWADs.

4. Input the absolute path into d_pwads to load, seperated by a comma with no spaces in between them.
For example, if you had a wad called "mycoolmappack.wad" and "awesomeguns.wad" located in "C:\WADS", you would put in, with quotation marks at the ends:

d_pwads "C:\WADS\mycoolmappack.wad,C:\WADS\awesomeguns.wad"

In this example, I would like to run "Eternal Doom III" but use weapons from "Vesper"

5. Type "web_reload" in the console and your wads "should" work provided that it is not using any stuff meant for other source ports otherwise the game will crash.

6. You now should be able to start a new game. If the game crashes, you may have to use console command to start a new map. Then you should be able to back out into the main menu and start a new game while selecting your desired difficulty.