This program has a list of all possible solutions to the game of 8. It can use the list to solve any randomly generated game. It will always find the most efficient solution. Press play to generate a new game. Press Solve to see the computer solve the game.
Inspired by this 6 puzzle by @Kinderlabor : http://scratch.mit.edu/projects/25535356/ To do this with the game of 15 would take terabytes to store and years to generate the list of solutions. I wouldn't have believed it, but apparently It has been done using distributed processing.