Last year, Neil decided he wanted to design the world’s most difficult 4 x 5 sliding block puzzle. To that end, he wrote a program to design sliding block puzzles, which he called SBP. You can get all the technical details of the program, and the puzzles he built, on Neil’s blog.
We also discovered, at least when it comes to sliding block puzzles, Neil has a nemesis, and his name (or his online alias) is Bob Henderson. Neil’s computer would creak and groan and spit out a difficult sliding block puzzle, and after confirming it (as in, “this puzzle takes 46,126 moves to solve!”), he’d set about to post the impossible puzzle to a puzzle site…..and thereupon, discover Bob Henderson had already posted the same puzzle, and with more elegant programming behind it.
So Neil would set about making a yet more difficult puzzle. And Bob Henderson would have done it first, and better.
It became rather comical with each iteration (to the rest of the family, not necessarily to Neil). Each time Neil announced he had been pwnd yet again, Peter and I took to howling “Henderson!” in the style of (take your pick), Captain Kirk shouting “Khan!”, Seinfeld growling “Newman,” or Sheldon from the Big Bang Theory screaming “Wheaton!”
We have no idea who Bob Henderson actually is. Neil is acquainted with many of the movers and makers in the brain-bending twisty and slidy puzzles world, but there is no Bob Henderson among them. So we added to our fun by speculating who Bob Henderson is. Many of the puzzle sites will indicate from where in the world a designer comes from, but Bob Henderson would only reveal that he was (probably) somewhere in the U.S. We speculated that Bob Henderson was either another puzzle-obsessed teenager like Neil, or some impossibly old crotchety genius determined to put upstart teens like Neil in their place. Anything else would be disappointing. Or Bob Henderson could be no person at all, but rather a supercomputer programmed by an evil genius to create increasingly difficult sliding block puzzles into eternity, or until the power goes out, whichever comes first.
I once asked Stan Isaacs, who knows all the puzzle people, if he knew who Bob Henderson was. He had a twinkle in his eye as he said, “I know Bob.” But he said nothing more. And so, the mystery persists.