what do I need to be able to run spiral in emacs? I can't find the package 'highlight

It’s in EmacsWiki.

You can install it manually and you’ll be good to go.

I think @volrath will drop it soon - EmacsWiki deps are a very bad idea in general.

it appears to be in Melpa (not stable)

@ghadi yes, you have to use melpa, not melpa stable

@bozhidar is right, I'm going to drop that dependency soon

@ghadi MELPA builds some packages from EmacsWiki, but they are going to drop this soon. Obviously something hosted on a wiki is hard to track in terms of stable releases. 🙂