I've been stuck on this for days and I can't seem to find anyone else having this issue. No matter how many fresh installs, youtube and online tutorials, I cannot for the life of me figure out how to play different doom WADs on my steam deck using ZDL. I have no issues getting it to run and play DOOM and DOOM 2, but when I try to play Haste, Sunder 2009, Italo, ANY other WADs, it only will launch Doom or Doom 2.   From my understanding, you have to add the WAD you would like to play in