Match four balls with the same number.
How to Play SortStack
Sort the numbered, colored balls into glass tubes containing four matching balls each. Select a tube’s top ball, then a destination with a matching top ball or an empty space. Green rims show legal destinations. A completed tube locks and adds an empty tube for more working room. The ball numbers also identify colors. Scroll sideways to reach more tubes on a narrow screen. Undo is free and unlimited; hints suggest a useful next move rather than proving an optimal solution. Classic offers Easy with unlimited moves, Medium with 50, Hard with 40, and Expert with 35. Relaxed removes move limits. Start by protecting empty tubes so you have space to rearrange mixed colors.
Frequently Asked Questions
What is Lock & Expand?
Four matching balls complete a tube. It locks, and a new empty tube gives you more room to sort.
Is Undo free?
Yes. Undo is free and unlimited.
What are the difficulty limits?
Easy: 3 colors, 5 tubes, unlimited moves. Medium: 5 colors, 7 tubes, 50 moves. Hard: 7 colors, 9 tubes, 40 moves. Expert: 10 colors, 12 tubes, 35 moves. Relaxed removes limits; Daily selects a difficulty for the day.
How are puzzles made?
Boards are constructed by scrambling a solved arrangement with reverse moves. This does not prove the shortest solution or guarantee completion within a difficulty’s move limit. Use Undo or Relaxed to explore.