Wolfenstein 3D defined the FPS genre in a way no one could have predicted. Just like the Gameboy defined portable gaming in a way no one could have predicted. Cartridge based computing and gaming offered something that disk (or disc?) based media never could: additional hardware.
The most famous example of additional hardware is the “SuperFX” chip that debuted with the SNES game Starfox. (It was in used in others in addition to a successor.) Most NES cartridges had other hardware too: mappers, sound generators, additional ram, etc.
You might consider this process cheating since the co-processor on the cartridge is much more powerful than the Gameboy Color’s hardware. From a practical perspective adding would have made a ridiculously expensive cartridge. However, when you think about it, is this any different than the SuperFX or SVP (Sega Virtual Process0r)? Who cares, it is just plain cool!
Go here to check out Wolfenstein 3D on Gameboy Color and more details on the “Wolf” co-processor.