Nov 17 was the Global Day of Coderetreat. I participated for this kind of event for the first time.
Coderetreat is a day-long, intensive practice event, focusing on the fundamentals of software development and design, away from the pressures of 'getting things done'.
The essence of the format is solving the same problem multiple times in consecutive sessions, each time with a different person.
I can confirm a saying that it's "the opposite of a hackathon". In both you have a chance to reset your mind by adapting a completely different mode of work for the duration of the event. But they’re also on the opposite ends of a spectrum: While hackathons are all about focusing on delivering value quickly (forgoing methodology), during a Coderetreat the focus is on methodology and there’s no value delivered by definition - the problem is chosen to be mundane, and the outcome ends up ritually deleted after each session. The only trace is what you learned.