@mkoff About SIGIL:
It is a Core Limitation, I recommend that you rename WADs in a more "coherent" way:
DOOM.WAD
DOOM_2.WAD
PLUTONIA_EXPERIMENT.WAD
TNT_EVILUTION.WAD
SIGIL_v1_21.WAD
Where to write to add ports? There is no normal life without Heretic, Hixen and Duke Nukem 3D!
There is Libretro cores for this games?
Recalbox developers only add open source cores, which already exist, if they focused on inventing a core for each game there will be no further improvement in Recalbox...
I recommend you use DOS for these games:
https://recalbox.gitbook.io/documentation/emulators/computosaures/dosbox