Click the board, then use the arrow keys or WASD. Z or Backspace undoes a move. On a phone, use the arrows under the board, or tap any square to walk there. Tapping a crate next to you pushes it one square. Undo is free, as often as you like.
The rules
- Walk the worker around the floor. Walls block you.
- Walk into a crate to push it one square, as long as the square behind it is free.
- You can't pull a crate, and you can't push two in a row.
- The level is done when every crate sits on a goal, the circles on the floor.
The game is often called Sokoban, after the original. The 7 levels here are the first ones from each pack of my Box Push app, made by my own level generator. For each one, a search checked the fewest pushes it can be done in, which the board shows above it. They go from 4 pushes up to 14 for Factory 4.
Dead positions
Most lost levels aren't lost at the end. They're lost a few moves in, when a crate goes somewhere it can't come back from. Learn these shapes and you'll see them coming.
Corners
A crate pushed into a corner can't move again. To push it out, you'd have to stand inside a wall. So unless that corner is a goal, the level is over. This is the first rule to learn, and the one that catches everyone.
Walls with no goal
A crate pushed against a wall can only slide along it after that, because you can't get behind it to push it away. If the wall runs straight from corner to corner with no goal on it, the crate will never reach one. In the drawing, every shaded square is one where a crate is lost for good.
Move the goal against a wall and that wall comes back to life. A crate on it can now slide along to the goal. The corners still can't, because a crate in a corner can't slide either way.
Two crates side by side against a wall
Neither crate can go away from the wall, and neither can slide along it, because the other one is in the way and you can't stand in the wall to push. They're stuck together. It only works out if both are already on goals.
Four crates in a square
The same thing happens in the open. Each crate in a 2 by 2 block is held in place by the others, from every side you could push. Any mix of crates and walls filling a 2 by 2 square locks up the same way.
How the shaded squares are worked out
Think backwards. Start a crate on each goal and pull it away in every direction you could, the way a push would have brought it there. Every square a crate can be pulled to is safe. Anything it can't reach is dead. The board above does the same check, and when a push leaves a crate dead or locked in a block, it says "This crate can't move to a goal anymore. Undo?"
Habits that help
- Before moving, decide which crate goes to which goal.
- Fill the goals furthest into a corner or a dead end first. Crates parked there won't block the others.
- Keep a path open so you can get around to the other side of a crate.
- Push a crate along a wall only when the goal is on that same wall.
- If a level feels impossible, undo back to the start and count the pushes you really need. The fewest pushes shown is a hint about how direct the route is.
Questions
Is this the same as Sokoban?
It uses the same rules. The levels are my own, made for the Box Push app, not copied from the classic sets.
Can every level be solved?
Yes. Each one was replayed from a stored solution and checked with a full search, which also found the fewest pushes shown above the board.
Do I have to match the fewest pushes?
No. Any solution counts. The number is there if you want a second challenge after you've solved it once.
Is there an app with more levels?
Yes. My Box Push app for Android has 240 levels in four packs, a daily puzzle and unlimited undo, and it works offline.
