A new cheat code for the Sega Saturn version of Doom has been discovered, 27 years after the game’s original release in 1997. This newly found cheat allows players to make walls in the game semi-transparent, offering a unique gameplay feature that was previously unknown.
Just from the screenshots in the tweet/article:
I would argue that is less transparency and more overlaying the skybox texture. In the city map with the Pinky you can’t actually see anything behind that wall, you just see the skybox.
Could just be “bad” examples but this makes sense. My understanding is that PC DOOM tended to use additive geometry in these cases so that the skybox is literally just a bigass box around the map. Whereas I assume the Saturn version had to do some magic to fit everything and may have used a different technique. Hence the ability to just overlay that texture over everything.