In case you missed it, the new 2025.04.05 release of Principia last week reintroduces #puzzles as a new level type you can create in the sandbox. Create and play custom puzzles in Principia, just like in the old days!
With this, there is also a new section for user created puzzles on the community site, which is bound to expand in the future: https://principia-web.se/latest/puzzle
The #OpenSource version of Principia continues to evolve, as #FreeSoftware available for #Linux, #Windows, #Android and more!