As the title states, there's extensions of the grayscale hallways.
Firstly, level -1 is great, but I feel the entities are a bit too overwhelming sometimes, considering the level should be void of entities, according to lore.
Instead the amount of entities should be sanity based (if possible), and should only stalk players in the beginning, similarly to smilers, before attacking them when their sanity drops too low, giving the impression you've gone mad.
I also think they are way too loud, they should have a much more stealthy approach to players (and not spawn right on players).
level 139 (-1): https://backrooms.fandom.com/wiki/Level_139.5
Level 139.3 (-1.3): https://backrooms.fandom.com/wiki/Level_139.3
Level 139.5 (-1.5): https://backrooms.fandom.com/wiki/Level_139.3