The story itself has been posted here.
What does that mean? Well, utopias are pretty hard to write anyway. Writing needs challenges for the characters, and that's trivially easy in a dystopia (everything is a challenge), a fake utopia (the challenge is to to look beneath the facade, and fight the secret enemy), or even imperfect utopias (the challenge is to solve the remaining problems). Iain M. Bank's Culture illustrates another way you can write about utopias and keep them interesting: by having an external foe as a challenge.
I avoided all those tricks. The challenge then was to write about a genuine utopia, one that people would enjoy living in, without any hidden flaws or enemies, internal or external. And these had to be real people doing things they wanted to do, rather than idealised people doing things they should do. Basically a real utopia has to contain internet trolls and various fanatics, and still be a great place for everyone.
The setting is a future Earth that is full-fledged techno-utopia, full of powerful artificial intelligences (with human-friendly goals, of course), uploads (human minds run on computers), massive technological developments, and the beginning of universal space colonisation.
In one sense, this made the story easier to write - nobody argues over the last leg of lamb needed to prevent starvation. In another sense, it made it much harder. Any human could desire to purge themselves of sinful thoughts, upgrade themselves to superintelligence, or copy themselves ten trillion times. And the AIs could perfectly grant them their wish - but should they? If so, do they let arbitrarily bad consequences happen? And if not, how do they go about forbidding things in a utopia? And what happens to disputes between humans - like when one person wants to join a group and the members of the group don't want to let them in? Can you prevent social nastiness - but then what about those people who want to be nasty?
You can read the story to see how well or badly I've answered these challenges. The Utopia was inspired a lot by Eliezer's fun sequence, Scott Alexander's Archipelago, and LARP. The general principles are that there has to be a functioning society behind everything, that people can become whatever they want to be (eventually, and after a lot of challenges, if need be), and that the good aspects of everything must be preserved, if possible.
To explain that last point: it's clear that tolerant liberal democracies are better places than repressive theocracies. But repressive theocracies will probably have certain positive aspects lacking in democracies (maybe a sense of place? an enjoyable resignation to fate or government?). The challenge is to take that positive aspect, fill it out, and make it available without the rest of the baggage. Similarly, the quote "death brings meaning to life" is nonsense, but there's something in that idea-space - something about contemplating the brevity of existence, and the perspective it gives - that is worth preserving. For some people or most people (or groups), if not necessarily for all people in all groups. Similarly, good outcomes often have bad aspects. So the engineering challenge is to separate the good aspects of all experiences from the bad, gaining the wisdom or experience without the intolerable pain and anxiety.
Since I tried to cram the maximum of ideas in, the story suffers from a certain degree of "tell, not show". Now, this is very much in the tradition of utopias (it's "Plato's Republic", not "Exciting Adventures in Plato's Republic (XXX-rated!!!!)"), but it is a narrative, and hopefully it's clear there's the potential for more - for much more.
In any case, I hope it works, and gives people something to aim for.
Thanks to all those, to numerous to mention, who have helped directly or indirectly with this. Have a great Holiday Festival!