Slide the tiles around the box until they appear in numerical order from the top left, with the hole in the bottom right corner.
On a touch screen, a tap does what a click does.
Click on a tile to slide it towards the hole.
A tile anywhere in the hole’s row or column can be clicked: it slides along with every tile between it and the hole.
On the keyboard, the arrow keys slide the tile next to the hole in the direction of the arrow.
Hint shows the next slide rather than simply making it. Nothing in Fifteen is forced by logic, so the hint plans a way to finish from wherever you are and tells you what each slide is for.
The plan puts the tiles home one at a time, and each step opens by naming the tile it is working on — “Working on tile 3:” — which stays the same until that tile is home, even while other tiles are moving. The rest says what this slide does: slides the tile into place, slides it closer, or slides it back a step, leaving the hole between it and its home (the hole sometimes has to go round it, which takes it further away for a while); or, for another tile, slides that one into place again or out of the way.
Follow it or go your own way: when you make a different slide, the next hint plans again from there.
These parameters are available from the ‘Custom type…’ option on the ‘Type’ menu.