In 1982, the British game designer Steve Jackson is editing the first Fighting Fantasy adventure gamebook, which he has co-authored with Ian Livingstone, The Warlock of Firetop Mountain. As he brings together his half of the book with Livingstone's, he notices that quite by chance, there are 399 numbered references in the adventure -- a number which is just begging to be rounded up to a nice, whole 400. So Jackson duly does so, adding an extra reference which is not accessible from any of the others and is there just to make up the numbers. The number sticks, and 400 references becomes the standard used for the vast majority of the 70+ books that will be published in the series over the next 42 years, with 'turn to 400' becoming synonymous with victory.
In 1984, though, the Fighting Fantasy range opens up to freelance writers, it having become apparent that Jackson and Livingstone cannot keep the best-selling series going on their own. The first book from an outside writer is by the American game designer Steve Jackson, a book called Scorpion Swamp. The American Jackson's book differs from what has come before in many regards, but crucially, it has multiple possible solutions owing to its premise that the player character can accept one of three missions from three different wizards before entering the titular swamp. Hence, in this book, section 400 is just a section like any other, not tied to victory or even a game over. Jackson USA would use a similar approach on the other two gamebooks he wrote for the series, Demons of the Deep (where the goal is always the same but you have multiple different options and approaches for the book's endgame) and the science-fiction based Robot Commando (which is somewhere inbetween the two, giving you complete freedom to go wherever you like and offering several entirely different ways of winning the game by defeating the invading forces).
There are a few other books where section 400 does not see you emerge from your adventure victorious, two of which were written or co-written by Paul Mason. No, not that Paul Mason.
Both of these books were published later on in the series' run, and are notable for their unusually mature writing and complex gameplay; in particular, The Crimson Tide has several unusual non-fatal endings such as giving up your quest for revenge to become a monk, although there is one 'golden' ending which is clearly preferable to all others. In both cases, Mason (or his co-author, Steve Williams, with whom he wrote Black Vein Prophecy) also appears to use the placement of section 400 to actively if lightly troll the reader.
