An interesting combination of developments:
Having read "games of no chance", I'm pretty confident that it's either Eliezer or someone who is trying quite hard to sound like Eliezer. Reasoning as follows, contains mild spoilers for "Games of no Chance" and also most fiction that Eliezer is known to have written:
1. The MC is dropped from a context where they know lots of math and game theory into a world that doesn't have those concepts.
2. The MC immediately starts talking about how they will use their superior math knowledge to take over the world, even before they have fully oriented to the situation (and, indeed, before they have any in-world reason to know that the lack of math is a feature of the world as a whole rather than the corner of it they were dropped into).
3. The MC treats their math knowledge as a sacred secret when teaching other characters. The other characters go along with it, and immediately recognize how valuable this sacred math is. To demonstrate that the other character understands the importance of math, they even ignore a deadly insult from the MC (that is, something somewhat rude the MC said, but was called out by the author as actually being a deadly insult in that character's culture).
HPMoR, Planecrash, and The Hero With a Thousand Chances all share this same pattern. I am not aware of any other author that tends to write this particular pattern, and particularly not with the same emphasis on decision theory adjacent stuff.
In particular, I'm looking at this exchange: https://www.glowfic.com/posts/7264?page=22
Sora: One of the 'mixed strategies' somewhere between 0% folding and 100% folding is a「Nash equilibrium」that leaves me indifferent to—"
Stephanie: "A 'Nash equilibrium'," Stephanie repeats slowly, sounding out the words. The phrase "næʃ ekwɪˈlɪbriəm" has failed to translate. It involves math, somehow.
Sora: "… okay! On the off chance that we've just struck paydirt I need you to lose a game of Rock Paper Scissors. You're wagering away your right to share this knowledge with anyone until I say otherwise."
Stephanie: Stephanie's indignance at this treatment is vastly outweighed by her curiosity about the forbidden gambling knowledge. She plays scissors to Sora's rock, wagering her silence on the matter, and commits to paying attention to what he has to say.
Incidentally I'm also pretty sure this is not written by only Yudkowsky.
@jacksonpolack Okay, point in favor of "inspired by Yudkowsky":
> Sora doesn't disagree. He'd figured his first Isekai Protagonist Invention would either be the wet sulfuric acid process or the movable type printing press, depending on Elkia's current branch of the tech tree, but it might end up being a less caustic recipe for soap. His skin isn't happy with the results either.
This seems a little bit too on-the-nose to be Eliezer. Wouldn't be the first time he'd left such an obvious callout to one of his previous works, but.
@FaulSname Funnily enough, this is part of why I think it isn't him, just someone trying to write in the same genre of rationalist-isekai-protagonist.
@FaulSname Actually, those are the two inventions provided by his dath ilani in previous threads. Keltham mourned he couldn't just invent the printing press.
I am personally quite confident that Syzygy is Eliezer plus a coauthor who plays serious poker.
@BenjaminCosman https://www.glowfic.com/posts/7264, although there's been another thread since.
Syzygy tried to upload an SVG icon for a quadricolor flag: check the mime-type of https://d1anwqy6ci9o1i.cloudfront.net/users%2F884%2Ficons%2Fvsd39uuvk1b8q154x5uog6_elkia.png. Syzygy has also used fancy CSS for the tables of rock-paper-scissors outcomes. I think this is strong evidence against Syzygy being Eliezer.
@Aevylmar I would resolve it YES if Eliezer is cowriting even if he's not writing the whole thing, NO if it's entirely written by another author who is asking him a large number of questions behind the scene.
for those who want to bet on the other possible answer, https://manifold.markets/JiSK/is-syzygy-on-the-glowfic-constellat-4280bdaa1413