"I wanted to know what a game about this kind of place would look like. With everyone just going about their daily lives. And you jumping from roof top to rooftop and scaling this monstrous structure."
I got really excited for this game when you referred to the section of
Kowloon Walled City; I hope you continue to referenced architectural section drawings to understand how sections shape space and create movement.
For details (or greeble) you should look at the drawings of
Atelier Bow Wow out of Tokyo. I think you could put back some of the daily-life references you were interested in initially instead of a typical vertical platform section with art assets (i.e. the hanging laundry as an architectural detail does a lot for the lived in feel of Kowloon Walled City).
For a more macro scale, I would look at architectural sections and see how different rooms relate to each other and how different heights effect this relationship. You could look at a number of buildings from antiquity or the renaissance, but in lieu of Kowloon Walled City you should check out
Gifu Kitagata Apartment Building by Kazuyo Sejima. The building is composed of a similar unit scale as Kowloon Walled City, but Sejima uses tetris like shapes to break between the floors, creating a less slab centric building, something a vertical platform would love (
section 1,
section 2,
section 3).
Another good reference for you would be the
Tower of David Caracas: an abandoned bank building turned slum. There is a really fascinating social structure that has developed exclusively within the tower involving taxis and shops that operate only within the structure. It would work well as a game level precedent because unlike most architectural sections, it divorces the idea of the bottom most level being the key real-estate and allows for a more interesting verticality in section. The famed architectural photographer
Iwan Baan also has some great photos from inside the tower.
If you are interested in breaking with orthogonality, these sections by Lebbeus Woods are often referenced by architects (
section 1,
section 2); they have a gritty vibe and are anti-orthogonality, similar to Kowloon Walled City.
Obviously the
Metropolis anime by
Osamu Tezuka and
Katsuhiro Otomo could be another great reference for you concerning section on an urban scale.