Oh man, Lists and Lists is fun. I was kinda bummed it was over so soon. Perfect for people who enjoy reading SICP or Little Schemer.
I'll have to try the rest now.
Edit: Most or all of these seem to be written in Inform (specifically Inform 6), a rather curious DSL intended specifically for text adventure games. Here is a fun writeup about misusing its successor language Inform 7 for something it wasn't really intended for.