Many years ago I was playing around with an Acorn Archimedes (RISC OS) anagram application. It wouldn't let me create anagrams of the programmer's name, William Tunstall-Pedoe.
It was called !Gravity on the Acorn Archimedes. It was written in BASIC (and possibly some assembler) and I remember it being a popular game at school to hack - change the number of planets, acceleration rate etc.
About three years ago I knocked up a quick BBC Basic program (RPCemu/RISCOS) to play around with some dithering algorithms; I ended up painting the results: