Difficult one to rate for me, I'm absolutely awful at 15 puzzle even at the best of times, and with these, I have very little concept of what the solutions are actually going to look like - I doubt I'd be that good at finishing them even if I could just swap tiles from anywhere jigsaw puzzle-style. A very choice few people would almost certainly appreciate the sentiment of the game though, and it appeared to be well-executed and well-built.
Viewing post in Prim d'avust jam comments
If you want to learn it I can recommend this page. It explains it in great detail and step by step.
http://www.waynesthisandthat.com/15puzzle.htm
Have fun and enjoy :-)