[WorldMaker]

A lot of code editors and IDEs already have folding indicators and indent guide lines which provide the sort of "context coloring" that is demonstrated in the article. (VS Code's language-server based contextual folding, especially.) There are extensions to add colors to those guide lines and fold indicators, but it probably says something about how generally useful it may be in that code editors don't default to that behavior.

(For instance, in JS I've come to prefer to un-nest structures as much as possible and the provided example hit some of my code smell receptors that I would refactor it and un-nest most of it, but that's my aesthetic preference here.)