Hello

Just one question- is it possible, to solve 15 game if grid is not square? I have written this game for 6x5 grid, however I've tried about 20 times I always fail to solve last row. So I started to think the solvability may depend on width/height ratio or something like that, but there's no info about that..
So I really hope somebody here can tell me if I'm just too dumb or game of this size is really unsolvable..

Thanks

nvm. Finally solved. Looks like in 6x5 there's a lot of unsolvable combinations..