NINTENDOOM is a patch WAD for all versions of Doom, including vanilla. It makes Doom look like a NES game, which uses a palette of only 54 colours.
If you think you know your way around a map give it a go again with this low colour mode. I tried to keep enough contrast in the palette so it can produce a readable look, but it provides an interesting challenge. I recommend you to mix it up with chiptune sounds replacement WADs or a Fluidsynth 8-bit styled soundfont (if supported by your port of choice) and 320x240 resolution for a cursed retro experience.
Keep in mind that some WADs feature their own PLAYPAL or COLORMAP lumps which may override those contained in nes_pal.wad. The order in which they are specified in the command line is important and nes_pal.wad should be specified at the end for the best results. The end results when used in combination with non-doom WADs that use incompatible palettes are unknown.
Credits: Sigvatr for the idea and ahefner for the NES palette values.
Will check out and record gameplay!