The warehouse puzzle
Classic Sokoban: a top-down grid. The keeper (you) walks in four directions. Boxes can be pushed (not pulled) into adjacent empty cells — one box at a time. Goal: every box on a target tile.
The puzzle's reputation for difficulty comes from a single mechanic: once you push a box into a corner or against a wall, it's stuck forever. A single mistake can render the board unwinnable. The puzzle is therefore less about reaching the goal and more about predicting which sequences of pushes lead to deadlocks.
Why it's beloved
Sokoban is the gold standard for puzzle-design purity. Tiny rule-set, no time pressure, no luck — and yet the puzzle is provably PSPACE-complete, meaning a general solver is computationally intractable. The best human solvers develop an intuition for deadlocks that no algorithm matches.
The original 1981 release had 155 levels. Forty years later, the community has produced hundreds of thousands. A handful of masters have designed levels that took the community over a decade to crack.
How to play
- You play a keeper on a 2D grid.
- Move the keeper up, down, left, or right.
- If the keeper walks into a box, the box is pushed into the next cell — provided that cell is empty.
- Boxes cannot be pulled, only pushed.
- Only one box can be pushed at a time — pushing two boxes against each other doesn't work.
- Goal: every box ends up on a target tile (usually marked with a dot).
- Walls are immovable; the keeper cannot walk through them.
Strategy tips
- Survey the board before your first push. Most Sokoban solutions are short; the difficulty is choosing the right pushes.
- Identify deadlocks. A box pushed into a corner (without a target there) is permanently stuck — restart.
- Watch wall-hugging. A box pushed against a wall can only be moved along that wall — make sure that's the right direction.
- Work backward mentally. Picture the final state and reverse-push boxes toward their start positions.
- Use undo liberally. Sokoban was designed with undo in mind; not using it makes the puzzle ten times harder.