SHIFT puzzle

"SHIFT" is a very difficult puzzle, unsolvable at first glance.
Not invented by myself, but found on the web where is was called "the most difficult puzzle in the world".
To solve the puzzle using mouse or keyboard, I wrote this Delphi-7 program.
Also the program can search for solutions in case the user gets tired trying.
Below are pictured two (half size) screenshots. The left is the original- and the right is a possible solved board state.
The puzzle consists of a board having 4 x 5 fields.
Blocks of size 1x1, 2x1, 1x2,or 2x2 are shifted until the red 2x2 block occupies the the fields at the bottom center.
The position of the other blue blocks is not important.

Some websites have an on-line version of SHIFT, but the primitive user interface is very frustrating.
Moves cannot be taken back and previous moves cannot be replayed.

This SHIFT program has the following options:
  • find solutions yourself (use mouse or keyboard to move. Moves can be taken back)
  • replay previous moves
  • have the computer search for solutions
  • save moves on disc
  • open moves from disk
  • print moves including picture of initial- and final board state
  • In-Line help information
I unviel that a solution counts over 100 - but less than 200 moves.
(the solution in the screenshot is not he shortest one)

Download "SHIFT" by clicking on the download (lightning) icon at the left top of this page.

Have fun! Interested how to program the search for solutions?
Click [here] to find out or load the complete Delphi-7 project.