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.
Yea, that’s specifically not transparency. Megaman X 4 had actual transparencies, which you can see here with the glass tube, next to a spotlight using the dithering method.