Great work Dashie Jinx, and an admirable first post! In some cases, the connections made in this theory are palpable; in others, my jaded 11 year strong egg-hunting self grows skeptic. Here's my view on each of the Circle/Level relationships.
Mombasa Streets / Circle 1: LimboA perfect fit. There's not much to say that isn't obvious here, but I will leave you with the
first lines of the Canto that introduces Circle 1:
Broke the deep lethargy within my head
A heavy thunder, so that I upstarted,
Like to a person who by force is wakened;
And round about I moved my rested eyes,
Uprisen erect, and steadfastly I gazed,
To recognise the place wherein I was.
True is it, that upon the verge I found me
Of the abysmal valley dolorous,
That gathers thunder of infinite ululations.
Obscure, profound it was, and nebulous,
So that by fixing on its depths my sight
Nothing whatever I discerned therein.
"Let us descend now into the blind world"
If that ain't a word for word description of what happens to Rookie when he wakes up, I don't know what is.
Tayari Plaza / Circle 2: LustThis one seems decently cogent, with the mission further developing the relationship between Buck and Dare:
Romeo: "She ever tell you what she wanted?"
Buck: "No.... never."
I do especially like the connection you made there with the victims of this circle not being able to see their lovers.
Uplift Reserve / Circle 3: GluttonyIt is here where I grow weary, thinking that maybe it is simply a strike of coincidence that things fell into place for the first two levels. I haven't played this level in years, but I can't think of anything very relevant off the top of my head. Yeah, there's dead zebras, but they haven't stuffed themselves to death, they were just killed by the covenant. The giant 3 is definitely something I'd be willing to accept as reference if the 8 other levels fell into place, but alone it could be anything. Hopefully more investigation reveals something about this level. I'd be interested in viewing the maps of Uplift Reserve.
Kizingo Blvd / Circle 4: GreedPretty neutral on this one. Yeah, Mickey blowing his way through the covenant defenses is
kinda like
Here saw I people, more than elsewhere, many,
On one side and the other, with great howls,
Rolling weights forward by main force of chest.
They clashed together, and then at that point
Each one turned backward, rolling retrograde,
Crying, "Why keepest?" and, "Why squanderest thou?"
if you consider the scorpion vs wraith events to be the clashing. As for overall connotations of greed, however, I don't remember anything off the top of my head. Questionable.
Oni Alpha Site / Circle 5: WrathThe river cross-relation is pretty compelling. Straight out the bag there's an identifying relationship. Everything else, well, not super relatable.
NMPD / Circle 6: HeresyI got nothing. Really.
Kikowani Station / Circle 7: ViolenceFits decently. First ring is a river, second ring is the suicides who relate to engineer and their (unwilling) suicide. You are indeed the harpy that cuts at them.
Data Hive / Circle 8: FraudShockingly accurate. Circle 8 is divided into 10 ditches, whereas in Data Hive you descend 10 levels. Fraud is clearly a theme in this ODST level, as Vergil notes when you meet the cop - "Hitchhikers may be escaped convicts".
Coastal Highway / Circle 9: TreacheryDon't really see it.
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There's a lot of stuff that adds up, but there's also a lot that doesn't follow. At points the relationships become exciting, at others they beg too many questions. Now, I do say this as someone who has only done a cursory lookthrough of Dante's Inferno; I lack the depth of knowledge that the composer Joseph Staten would have. It is very well possible that simple allegories exist and we are missing them, and I hope that's true, given how some of these seem to work so well. Parts of this feel great, but we must remain cautious, and ensure we don't find things where they aren't.
Additionally, I would like to posit a co-opting theory: That the internal levels of mombasa streets must be played in a specific order that
does relate aptly to the circles. For example, Starting from Mombasa Streets, you may choose to play NMPD first. There's a wealth of different orders you can run the game in. This means we would have to figure out which circle most cogently fits with which circle in a nonlinear fashion.