Hello
CORE doesn t support pk3

## RECALBOX - SYSTEM PRBOOM ## Put your DOOM 1 and 2 games (and their associated mods) in this directory. Put your soundtrack in the directory ./game-musics DOOM games must have a ".wad/.iwad/.pwad" extension. DON'T ERASE "prboom.wad".

https://docs.libretro.com/library/prboom/