Link to the simulation code: https://github.com/jasmcole/Blog
And if you haven't read Seveneves yet, it's definitely a Neal Stephenson book and will not disappoint.
I agree with the first two thirds of what you've said, but not the last third - which parallels my feelings about the book.
The third part of the book felt like it was meant to be a full-length sequel to Seveneves, but was cut down to a novella-length post-script.
The last part is not as frantic as the first one, for good reasons. Nevertheless there are a lot of huge orbital machines and political plots that keep it going. Maybe there is some unbalance of tension between the two parts but I enjoyed the last one too.
I feel like all the folks (including myself) who really enjoyed the book believed that the "Seveneves" was an intentional palindrome, and the two distinct parts of the books were intentionally mirrors/foils of each other. Without that assumption, I can see how the second part of the book would feel arbitrary.
Maybe I'm not a reliable-enough reader, but I didn't particularly see a palindromic effect in the last part of the book.
(Which to me still feels like the last third - to me, the book feels like the book has three sections: the setup, the survival, and the aftermath. I haven't read it in long enough to see if it's actually split that way in any sort of specific "Part 1, Part 2, Part 3" way.)
Well, I have to disagree regarding Seveneves. I was always a Stephenson fan, until I tried to read that book. Gave up in part three. It also left a sour taste, which resulted in me no longer caring about further books from him.
Damned good book, too. Well, the first half at least. Your mileage will vary about the other half.
Interesting; this is reminiscent of the TV show "Space: 1999" about the Moon being blasted out of orbit and across the galaxy. While the premise was ridiculous, the show's first season was very quirky and quite enjoyable and explored some interesting themes. The second season, not so much.
There's a recent (2022) game called Ixion with an exploding moon premise. I initially saw it promo'd during a Steam sale, didn't buy it based on some very critical reviews regarding gameplay, and then forgot about it until seeing it mentioned in the 1d6chan Grimdark article.
I spoiled as much as I could short of playing the game, and then skipped through a full play-through on Youtube.
https://www.youtube.com/watch?v=DvPyoPRgrFQ is a good synopsis (full game spoilers). The main writer did an AMA on Reddit with some questions answered, but also made it clear that some things were simply unfinished, or just left up to interpretation.
<< very critical reviews regarding gameplay >>
Ehhh, is definitely not everyone's vibe, but I've very enjoyed my two playthroughs.