Maybe it's because I got Sonic Racing Crossworlds at the same time (Amazing, BTW), but World just feels so sluggish and uneventful in comparison.
There's movement I haven't learned, and maybe that'll be the spark I need, but right now I'm playing this game with the straightest of faces.

The last mirror seemingly breaks the whole theory, since that one leads out of the Nowhere. But with Alone unable to come with him, Low yearns to return for her. As long as that's true, he's still trapped in a way. In that sense, the outside world is also a reflection of the Nowhere for him.

This is why travel is done via mirrors. Each one is a different reflection of the same place through Low's imagination. It's only by not using a mirror, by not looking at a distorted reflection, that the Spiral's true form is revealed.

The monsters are all Otto as well.
Monster Baby treating them like its playthings.
The Supervisor lashing out when she doesn't see what she wants.
The Kin forcing kids to perform again and again until they get the act that they want.
The Hypnotist and the Institute's role in all this is obvious.

The Carnevale represents how Low felt expected to 'perform' in Otto's experiments. To appease Otto, like Noone, Low was expected to recount his nightmares with increasing detail or else face his frustrations. It wasn't helping Low so, to him, it must've seemed like it was for cruel entertainment.

The Candy Factory represent the surveillance Low feared from Otto. This we can actually see in the game itself, as he hides under the bed whenever he approaches the door. Fusing it with sweets is likely a result of Otto foisting sweets implied to be sedatives before he begins his 'surveillance'.

The Necropolis represents the isolation Low experienced. It is dusty and dead, miles from civilisation. Through Chapter 4 of TSON and the basement of the Institute, it's implied that patients like Low were isolated from other children due to protocol and possibly Otto selecting his 'test subjects'.

Oh, hey! That's me! I thought I recognised that splashtag from somewhere.

The aim was to hopefully use the extra height to jump over the Booyah Bomb, but I guess it just ended up as a panic Splashdown. 😅

Oop. No. The door's for an achievement, apparently.
Shame. But that's how Little Nightmares be.
Once again, BRING HER BACK!!!

MORE SPOILERS!
I got semi-spoiled on the twist going in, thanks to a piece of merchandise. But I didn't expect them to kill her! Nor to WATCH HER DIE ON SCREEN!!!

I did notice a locked door right before the final boss. Maybe there's an additional ending? Maybe she lives? Maybe I can stop mourning?

I'm not disappointed, I'm just... whelmed.
And admittedly, Monster Baby and The Supervisor might be some of my least favourite Residents in the series. Supervisor ranks 11th out of 13 just beating The Lady, and MB drops right to the bottom.
They're just not present enough. There's so much downtime.

Sage would be a perfect addition now of all times. I feel like she'd play off Stone very well, and open up some wholesome and melancholy moments for the both of them.
Plus it's no secret how Stone feels about Robotnik. Raising his daughter now he's gone would be a nice follow on to that.