That's different, though. That's breaking out of DOOM, not implementing DOOM in DOOM. You might argue that the "reference implementation" (i.e. ID's DOOM) is the "canonical" doom and thus this counts but... it's still not "DOOM implemented in DOOM", it's running x86 code.

Not to take from that achievement away, though, I just don't think it fits in the context of this post!

Here's some theoretical background on DOOM's Turing-completeness: https://calabi-yau.space/blog/doom.html

In the genre of "an implementation of game X on an accidentally Turing-complete Y", it never hurts to bring up Tetris implemented in the Game of Life: https://codegolf.stackexchange.com/questions/11880/build-a-w...

I don’t think that means anything though. Doom the game is not a Turing complete programming language. You could write doom in the underlying C and then have it run on a screen in game but that still wouldn’t be doom running doom.

In fact now I’ve confused myself, what would constitute doom running doom?

You have!

I think what is being discovered right now is whether DOOM itself is Turing complete, and if so, can you program DOOM inside of DOOM by making a computer inside of DOOM composed of DOOM monsters and map features that, when ran, recognizably played DOOM.

Sum up: creating a computer inside the game of DOOM and programming that computer to itself play DOOM would constitute DOOM running DOOM

Does the Babbage Engine run Doom?