# Blindfold Slide Puzzle

About two years, I created Blindfold Tile Puzzle, based on the game 2048.

2048 is played on a 4 by 4 grid, where you combine identical numbers to produce their sum.  Hence, in the above puzzle, with line three reading: 2, 2, 4, 32, you can combine 2 plus 2 to generate a 4, resulting in 4, 4, 32, open-space.  Then you can combine 4 plus 4 to generate an 8, resulting in 8, 32, open-space, open-space.  You win the game when you combine 1024 plus 1024, yielding 2048.   I’ve heard the game called “Candy Crush” for math geeks.

Once Blindfold Tile Puzzle was published, fans starting asking for the sliding tile puzzle known as 15, also called the Boss Puzzle, Game of Fifteen, and Mystic Square.   It’s played on a 4 by 4 grid of numbered square tiles, from 1 to 15, in random order with one tile missing.   The 16th space is empty.  The object of the puzzle is to place the tiles in order by making sliding moves that use the empty space.

Originally, I thought this game was too boring, but getting several requests each month changed my mind.  I built the game, and started testing it recently.  Here’s the Wikipedia history:

• It was invented by Noyes Chapman, a postmaster in Canastota, New York, who is said to have shown friends, as early as 1874.
• Copies of the improved Fifteen Puzzle made their way to Syracuse, New York, by way of Noyes’ son, Frank, and from there, via sundry connections, to Watch Hill, Rhode Island, and finally to Hartford, Connecticut, where students in the American School for the Deaf started manufacturing the puzzle and, by December 1879, selling them both locally and in Boston, Massachusetts.
• The game became a craze in the U.S. in February 1880, Canada in March, Europe in April, but that craze had pretty much dissipated by July. Apparently, the puzzle was not introduced to Japan until 1889.

Some facts for math geeks:

• In 1879, two mathematicians proved that half of the grid layouts for the game are unsolvable for the 15 puzzle.  Larger puzzles, such as 5 by 5, do not have this limitation.
• For the 15 puzzle, the optimal solution takes from 0 to 80 moves.
• For the 9 puzzle based on a 3 by 3 grid, the puzzle can be solved in less than 31 moves.
• For the 24 puzzle based on a 5 by 5 grid, the number of possible positions is 7.65 times 10 to the 24th power, which is absurdly large.  In 2011, it was computed that the puzzle could be solved in as little as 152 moves, and as many as 208 moves.

You can download Blindfold Sliding Puzzle here.

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