About this game
Sort Stack is a calm but tricky colour sorting puzzle. Each tube holds up to four balls. Move one ball at a time until every tube contains a single colour. Every level is generated fresh and is always solvable. Clear a level to earn bonus time and move on to a harder one with more colours.
How to play
- Tap a tube to pick up its top ball, then tap another tube to drop it there.
- A ball can only go onto an empty tube, or onto a ball of the same colour, and only if there is room.
- Sort the balls until every tube is empty or full of one colour.
- Clearing a level adds bonus time and starts a new level with more colours.
- Use Undo to take back a move, or Reset level to start the level again.
Controls
| Keyboard | Keys 1-9 pick a tube, Z to undo |
|---|---|
| Touch | Tap a tube, then tap another |
| Mouse | Click a tube, then click another |
| Pause | P key or the pause button |
Tips
- Look at the whole board before you move. Find the colour that is easiest to finish first.
- Keep at least one empty tube free. It is your most useful tool.
- Dig for buried balls by moving the ones on top into a spare tube.
- Avoid stacking balls on top of a different colour unless you have to.
- Undo is unlimited, so test an idea and take it back if it does not work.
FAQ
Is Sort Stack free?
Yes. Sort Stack is free to play in your browser, with no download and no account.
Is every level solvable?
Yes. Each level is built from a solved board using only moves that can be reversed, so a solution always exists.
Why is there a timer?
The timer turns a relaxing puzzle into a score challenge. Every cleared level gives you extra seconds, so good players can keep going for a long time.
Can I play with a keyboard?
Yes. Press the number of a tube (1 to 9, and 0 for the tenth) to pick up or drop a ball, and Z or Backspace to undo.
Is my best score saved?
Your best score is saved on your device, in your browser. It is not sent to any server.