This is a generative homage to the gem puzzle, said to be invented by Noyes Palmer Chapman in 1874. It's also known as the boss puzzle, 8 puzzle and 15 puzzle (depending on the number of pieces).

Click on a piece of the puzzle to move it to the empty space. To solve the puzzle, you must get all of the pieces in numerical order from top left to bottom right.

To scramble the puzzle, type "s", and to reverse the scrambling (solving the puzzle), type "r". If you type a number x from 1 to 9, you will get a gem puzzle with x by x pieces. Type "n" to toggle the piece numbers showing.