This game began on CompuServe in 1989, and the official rules are still the ones that were published on CompuServe in January 1990.
There have been changes to the game over the years, but the players have never sanctioned a revision of those rules, which now look rather quaint.
Being uncodified, the changes to the game are scattered over 30 years of forum exchanges. We give this the grand name of established precedent and players are expected–somehow–to know it, and to remember any new rules. The 'Real' Rules presents this precedent as annotations to the original rules. But while rules are designed, precedent accretes. Rules can be expected to be internally consistent. But the precedent is not all consistent with the rules or even with itself, because of changed attitudes over time. As a consequence, the The 'Real' Rules are rather bulky. Because, instead of having a hard-and-fast rule for a given situation, to be impartial, it reports what is sometimes divergent opinion.
So, quirky as it might seem, this page offers three sets of rules.
The Basic Rules are the simplest and shortest. They take a single A4 page, and do not concern themselves with special cases. They are all that you need to start playing.
The 'Real' Rules are for when you have to deal for the first time, and encounter a puzzle, such as when to combine similar definitions, or what to do when a player makes a mistake, or when you do. They would take up about three A4 pages if printed, but most of the rules have a button called Comment. Press the button and you get ... probably more detail than you want. With every button pressed to reveal the text behind it, The 'Real' Rules would take up about fifteen printed A4 pages.
Finally, there are the 1990 Rules, which are still official, despite being sadly out of date. They take up four A4 pages, partly because of the space they devote to software that went obsolete a generation ago, and partly because of redundancies that seem to bear witness to hasty revision.
The first and last of these are also presented as PDF files for download. The 'Real' Rules are not, because PDFs do not support collapsing text, and a picture of a button marked Comment is not useful.