OK, I have another one done. This time it should be compiled for the gp32 correctly. The source code is with this one as well.
http://www.geocities.com/crazydwarf12/fifteen.zip
Right now you just try to get the numbers from 1-15 and then the blank piece. I'm thinking about adding a menu that lets you choose what order your trying to go for though. If anything doesn't work or if you have any suggestions about the code please tell me.
Edit: pressing B now changes whether or not you move the squares, or the blank spot.