Most projects I admire are ones where the solution is simple and easy, usually due to the immense effort of the author in understanding and abstracting away the complexity of the underlying problem. Here are some examples of gnarly domains:
Dates, times, and timezones and some Hacker News comments showing it’s even more complicated, and an XKCD to cheer you up
Package managers:
General problems, SAT solving - in mamba the conda replacement, XKCD
“Dependency hell” is a colloquial term denoting the frustration resulting from the inability to install software due to complicated dependencies. From the review we conducted one cannot conclude that the problem is solved.
REST/HATEOS
https://en.wikipedia.org/wiki/HATEOAS
https://medium.com/@andreasreiser94/why-hateoas-is-useless-and-what-that-means-for-rest-a65194471bc8
https://www.mscharhag.com/api-design/hypermedia-rest
https://www.linkedin.com/pulse/hateoas-question-nikhil-kolekar/
https://levelup.gitconnected.com/love-it-or-hateos-it-3f8d5844e736