u/ErrorCode40443

1.Gambling Room

2.Stan Hallway

3.Dock 99(main game)

4.Cabin Room

5.Pandemonium(Ultra kill) Room Easter egg

6.Backrooms

7.Just like the picture.

I'll leave some others in the comments below.

And if you come across another rare room in the above circumstances, please post a photo in the comments.

These are just some of my personal thoughts. Please feel free to contribute more opinions and ideas in the comments!

The script for this ending is in the image.