The BBC game Exile had a "novella" that came with it - the story of how things came to be before the player arrives. The copy protection had you look up a page number, line number, word number to proceed. Fun stuff. (I just found the text! http://inventivity.co.uk/exileami/novella.htm) (And the game! http://bbcmicro.co.uk//jsbeeb/play.php?autoboot&disc=http://...)

In fact, how they squeezed what they did out of the BBC B is amazing.