This was built in September 2022, and it's still pretty mind-blowing today:

https://madebyoll.in/posts/game_emulation_via_dnn/demo/

https://madebyoll.in/posts/game_emulation_via_dnn/

Hook world state up to a server and you have multiplayer.

2025 update:

https://madebyoll.in/posts/world_emulation_via_dnn/

https://madebyoll.in/posts/world_emulation_via_dnn/demo/