So it could run Doom?

Yes: https://github.com/robertcprice/nCPU?tab=readme-ov-file#doom...

Oh I forgot to Doom scroll.

Can we run doom inside of doom yet?

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Doom it's easy. Better the ZMachine with an interpreter based on DFrotz, or another port. Then a game can even run under a Game Boy.

For a similar case, check Eforth+Subleq. If this guy can emulate subleq CPU under a GPU (something like 5 lines under C for the implementation, the rest it's C headers and the file opening function), it can run Eforth and maybe Sokoban.