I’ve always wanted a coding project like this, that has a lot of breadth rather than depth.

By that I mean it would take a day or two to set up the basics and then I could keep adding to it, an hour here or there, for years.

The problem is that when I tried this a few times with various games, the breadth ended up having nothing to do with coding. Perhaps there just isn’t a kind of coding task/problem/toy/gadget that works this way.