Inform 7: having something off stage at the start of play

Dim Lit Room is a room. "[if unvisited] This room is the most disturbing thing you have ever seen in your life. The thing that disturbs you is behind a glass wall.[otherwise if glass wall is closed] The room still disturbs you but the shock has worn off. The entire room is made of metal. The thing that disturbs you is behind a glass wall.[otherwise if glass wall is open]The room still disgusts you a bit, the entire room is made out of metal. To the east is an open place where the glass wall used to be."

A desk is here. the desk is a supporter. glass pieces are off-stage. a page is a portable supporter on the desk. a paperweight is on the page. the glass wall is a closed scenery door. the glass wall is a breakable wall. the glass wall is east of Dim Lit Room. the glass wall is west of the Room of Horrors. Understand "paper" as page.

is there a way to start the game with somthing off stage?

All you have to do is avoid specifying where the object is, and it will start the game off-stage. “There is” is a useful phrase in this case:

There are glass pieces.

Buy you can also do:

Glass pieces are a thing.

Curious that you can say this:

When play begins: now glass pieces are off-stage.
…but you can’t declare them off-stage as an initial state. But it’s not really a problem in this case.