That's pretty neat. I wonder how it works. It's not obvious to me at all how to build something like this, as the program doesn't know the sequence in which the player will reveal the tiles.

I also once made my own variant of this (just like gregfjohnson's idea): A "lucky minesweeper" where luck can be toggled on/off at any point during the game: https://github.com/yshklarov/minesweeper

He's written a bit about how it works here: https://www.chiark.greenend.org.uk/~sgtatham/quasiblog/mines....