“Hey, looks like you’re killing demons. Need help?” - Clippy
The word document is not "running" Doom (the actual work is done by a dll that is included in the word document). The word document is instead used as a screen (never thought I'd wrote that) to display each frame.
The question is, what else can you call from the dll. Doom is self-contained, so the VBA just passes the inputs to it and gets a new image back. The dll also has to match the architecture, right? So not portable.
It's a shame, I figured something clever had been done in VBA.
The most astonishing thing to me is that after all these years people still keep finding new targets to port to.