Starting position: -1 denote empty space The empty space is in lower right position. Solve puzzle by moving space to the bottom right with the numbers in order. 6 possible directions are symbolized by 4 0 \| 3--*--1 |\ 2 5 (i.e. 0 = up, 4 = in, 5 = out) The solutions given are for a starting position of "diagonal swap" as this is also used in the cubes puzzles on this site. Solutions for other starting positions of "offset" and "reverse" and "reverse offset" solutions may also be available in breadth first search program for cubes puzzle. A swap of the last 2 tiles is done if the puzzle is not solvable in starting format.