Around 2005 I designed a version of the classic 15 sliding block puzzle, and called it "Janus" after the Roman God who had two faces.
The puzzle was entered into the IPP design competition and you can see that version here
I recently found that a new version had been made and was on the Russian twistpuzzle forum, made by Plut'on. I thought it looked great and he had kindly credited me with the design. Not sure how he worked out the layout as he would not have had access to the puzzle (I have both the ones made for the competition), so a nice bit of puzzle solving from him.
So I got in touch via the twistypuzzle site and we exchange a few messages before a deal was struck, he would make me a copy and send it to me. I also found out his true identity - Dmitry Andreev (Plut`on), who is well known in the twisty puzzle world.
Here is the version he made for me;
The puzzle is a two layer puzzle, with each layer being an independent sliding block puzzle. However, the elements that go to make up each number are split over the two layers. This obviously means that you have to solve both puzzles, with sometimes limited information about the piece, so that the two layers make up the correct numbers.
And then just to add a bit of interest, there is a parity switch on both sides, enabling the 14 and 15 to be switched over. This was the inspiration behind the original puzzle, I wanted to be able to have a puzzle that would solve the 14/15 switch, so having the pieces that would change from one digit to another enabled this.
This did remind of another idea I had for a similar puzzle - now just need to get my act together and get it made!
Thanks again Dmitry - I think the version he made is actually nicer than the original, and does make it easier to see the numbers.