I started typing: You definitely dreamed that -- and then suddenly I realised exactly what she was remembering. It wasn't XOR, or a Spectrum game, but it was a video game of the era.I had COMPLETELY forgotten that game XOR and would never have remembered it on my own! The only image which sprang to mind (before looking at screenshots to visualise the chickens and fish) were those light blue masks, but oddly enough I have quite a clear "memory" of one single blue mask, one side of which "flickered" several times until the whole mask detached itself from its black background and moved around freely. I suspect this was a dream... unless possibly there might have been some kind of fancy video intro? (well, fancy in Spectrum terms). Quite strange, as I really seem to "remember" this.
NOW: Can YOU work out what Lucy is talking about?
(Solution at the back of your Usborne Detective Book.)