One empty space. Plenty of possibility. Slide a numbered tile into the adjacent empty space. Arrange the numbers from left to right, top to bottom, with the empty space last. Begin with 3 × 3 boards, then explore classic 4 × 4 puzzles. Undo and guided route hints are available. Published by GEMDUCK LIMITED. Free to install on Android. Contains ads. See Google Play for current release details and optional purchases. Official gameplay screenshots and more games: https://gemduck.com/play/index.html