Some note in Sub10 hints that the Plan was created at the time of the Core, Lighthouse and such, with materials that spanned a structure between layers. And later with the Root, Shiva used that previously existing structure to expand the Submachine along it.

Right?

The Plan was created and I think Shiva was built primarily to fulfill the blueprints of the plan, but I think when they asked that question, Shiva did something totally different to what they had in mind. Makes sense to why some called it a "glitch"

Though others in the sub-net might call it a miracle.

If that's the case, then what did the player exit to? What is the world outside of the SubMachine?

To world outside Submachine is a mystery even greater than Submachine itself.

All the more reason that we should get some answers about it.

I was replaying the series and came across something that I do not remember being explained:

"Once there was a man who said he knew what was happening after Murtaugh left.

Since then that man left us as well."

Have I missed anything?

Not really. We all thought we were this individual that left the exploration team, but no so anymore!

Possibly this man went on to become the Holy Usher.

Its the only explanation I can think up of that fits with what we know of this individual. He knew exactly what's going on and is a perfect candidate to be teaching his disciples the History of Submachine and Path of Murtaugh far off in the future.

I had a short of discussion on who would the holy usher be. That note in sub10 and the note with the man who knew about Mur were the most mysterious. I simply love the connection you mde there it makes pretty sense. However,who is the disciple? Anyone else thought it might be the player?