[IshKebab]

I saw a project a while ago that was a non-Git version control system that used the Git disk format. I thought that was a pretty great idea. Totally compatible with all of the existing Git stuff, and the Git disk format is pretty good, but you can avoid all the UX mistakes Git made.

[zhengyi13]

Perhaps it was OpenBSD's http://gameoftrees.org/ (git -> got)?

[martinvonz]

I'd like to think it was my project (https://github.com/martinvonz/jj), but other possibilities include Gitless (https://gitless.com/) or Bazaar (https://bazaar.canonical.com/).

[IshKebab]

It was your project! I still haven't tried it yet I'm afraid but it looks very well designed.