And then there was the Frenchman who buried a golden owl and sent readers off to find it. He went into hiding after receiving death threats from desperate treasure-hunters.
Now, in the increasingly hysterical months before the millennium, there is Eternity - a jigsaw puzzle with no picture - but a pounds 1m prize for the first person to complete it correctly. Excited buyers already have pound signs in their eyes.
The 209-piece puzzle was invented by Christopher Monckton, a former adviser to Margaret Thatcher, who now offers his services as a freelance troubleshooter "for governments, corporations and individuals".
He claims the puzzle is "cheat-proof" and that it is as likely to be solved by an autistic child with highly developed spatial awareness as a bored teenager or bedridden pensioner.
Even Mr Monckton, after spending 14 years creating the puzzle, says he has only completed it once. "This cannot be solved by computer geniuses and mathematicians using complex formulae, which is the beauty of it," he said.
"It is simply a question of sitting down and doing it. You might find that you fit together 205 pieces and then the last four won't fit and you have to start all over again."
The prize fund will be raised from sales of the pounds 29.99 puzzle. Despite having convinced a firm of London insurers to underwrite the prize in case it bombs, Mr Monckton admits he has not taken out indemnity against any irate players who may end up hurling the game out of the window and causing serious injury to passers-by.
"It is a hard task, but there is a lot of prize money and I think people will enjoy it," he said.
Generations of adults who grew up wrenching the Rubik cube apart in frustration may not agree.
This unusual type of jigsaw puzzle originated 100 years ago in Japan, but had only 12 pieces. All are asymmetrical and each one is different. An average home computer can solve the 12-piece version in one second. But for every two pieces that are added, the time taken to find a solution is doubled.
By Mr Monckton's reckoning, it would take a computer expert 130 million billion years to solve his 209-piece version. "The universe has only been around for 10 billion years. There is just no cheating possible," he said from his home in Cyprus, an island on which he may well have to take permanent refuge if players' frustrations boil over.
Mr Monckton has tried his hand at many business schemes and admits he is hoping to make himself a fortune with Eternity. He describes his interests as ranging from classical music to motorbikes and "recreational mathematics", and proudly lists his achievements as "problem-solving for governments".
Lady Thatcher was the recipient of one of his prototype puzzles and reportedly spent several years hunched over the 12 pieces until she was forced to ask for help.
The puzzle arrives at the London toy store Hamleys next month, where a window display will announce: "Eternity is here". The game will also be sold in Woolworth and Argos stores. Hamleys spokeswoman Eva Saltman said: "The great thing about it is that the initial perception is that it is easy. Everyone thinks they could do it, but it is very intriguing. They quickly find out that they can't.
"It's not going to be a computer boffin who solves it - I think it will be somebody totally unexpected, who looks at things in a different way.
"We have checked on the legalities and we were given guarantees that the money is there to pay the prize."
Participants will have until 30 September 2000 to complete it. If no one is successful by then, the deadline will be extended until 30 September 2001 and so on until 2003 when the future of the puzzle will be reconsidered.
But there are clues available. Mr Monckton has also invented three smaller puzzles, with between 10 and 20 pieces. Anyone who solves those can apply to the manufacturers for the locations of up to five pieces for the big jigsaw. Mr Monckton hints that more clues could be made available after September 2000 if no one succeeds.
On completion, the player must trace his solution onto the grid provided and post it to the judges. All solutions will be date stamped on arrival and held in a secure location until the deadline. The correct solution with the earliest date stamp wins.
In case that proves too easy, Mr Monckton is already planning to launch a 400-piece version with a pounds 10m prize. All blunt instruments and dangerous implements should be removed from participants in advance.Reuse content