Tuesday, 19 July 2016


Now here's an interesting type of puzzle I got to play with for the first time. This one is called Twins (although there are 3 pieces but there's a reason) and this was Gary Foshee's IPP35 Exchange Puzzle.

Many puzzlers may already know Gary as the designer of the famous Lunatic Lock as well as the highly sought after and very rare Open/Transparent Lock.

Twins comprise three odd shaped pieces of light and dark coloured cubes glued together. The object of the puzzle is to "put all three pieces together so that the following conditions are met:-

1. Each light cube is connected to another light cube by a cube face
2. Each dark cube is connected to another dark cube by a cube face
3. The shapes formed by the light and dark cubes are identical. Mirror images are allowed.

(NB- the solution (at least the one I have) results in two pairs of identical light and dark shaped pieces; now you see why they are called Twins?)

Usually I am not too keen on such puzzles because I have to consider the various parameters (and many puzzles of this sort tend to have quite long winded and complex conditions to adhere to) during the solve. But in this case, the conditions were relatively few and simple to understand.

The three pieces look rather innocuous and the goal didn't appear to be that difficult, but I found it surprising challenging and it took me quite a while of fiddling before I finally came to what I think is the solution. I have been told before by another seasoned puzzler that the best puzzles are those that are simple looking with just a few pieces, but yet very challenging. The Twins is one of those puzzles.  

Unfortunately I am not 100% sure if my result is the correct one. I have emailed Gary but have yet to receive a reply. So if anyone else has solved it correctly, please drop me a note so that I can check my solution against yours.


  1. I made a computer analysis of this puzzle (and other similar ones with different pieces.) My program puts the pieces together so at least one face of two pieces touches each other.

    My program did not find solution.
    The reason for that can be:
    1. My program is wrong :)
    2. The pieces don't touch each other by whole face.
    In either case, could you send me your solution?

  2. Sorry, we have found the solution.
    The definition of the pieces had a mistake.