Was it this one? https://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/unta...

I went and found this game again relatively recently. It reminds me so much of decoupling and refactoring software or vice versa. I spent a few years occasionally trying to remember what distant memory of an experience decoupling reminded me of.

I quite enjoy both. Whilst simultaneously kind of hating the process.

Incredible sense of clarity once you've resolved everything that was stepping in the way of understanding. Moments of despair and frustration. Sense of progress combined with feeling this could be never ending. Iteratively trying to step towards something better. It all seeming worth it in the end. So many parallels.