[I7] Hidden room

How would one code a room not connected to anywhere but keep a different room as the one the player starts in?

"Testing" by "Phillip J Rhoades"
The story headline is "A testing zone".
The story genre is "Theoretical Fiction".
The release number is 1.
The story description is "Some description".
The story creation year is 2018.

Release along with the "Quixe" interpreter.

The Chamber is a room. "A spacious, empty room. There is a hallway to the north.". The player is here.

The Hall is north of The Chamber. "What a lovely hallway! There is a chamber to the south."

Isolation is a room. "An isolated room, connected to nothing."

By default, the player starts in the first room you declare. If that’s not what you want, you can always override it with eg. “The player is in the Yellow Room.”

Inform won’t make any map connections unless you tell it to, so creating a room with no entrances or exits is easy. “The Green Room is a room.”