Fifteen Puzzle Classic

Across a 4x4 grid, numbered tiles crowd fifteen spaces and leave one slot vacant. In Fifteen Puzzle Classic, pieces marked 1 through 15 slide through that gap inside a square board. The puzzle ends only when the full set sits in ascending order from the top row down. The name comes from the highest tile number, fifteen. Time and move totals record each completed run.

How to play?

Select a tile beside the space to shift it into the gap. Only neighboring pieces move. Build the top line with 1, 2, 3, and 4. Place 5 through 8 on the next line, then 9 through 12. Finish with 13, 14, and 15 in the last row, leaving the final space empty.