This seems to be the first project I’ve done entirely under Git version control, so I can tell you that I started it in June 2017. In January 2020, I’m still tinkering with it.
Click here to play it.
It has full history, with undo and redo, and the history lives in the URL, so that you can bookmark games or save URLs to return to them, or share them.
It also has a handy “lock” feature so that after you finish the current game, you can’t just start a new one.