Puzzle guide

Three short guides

• Reading a jam

  What really blocks the hero, why a truck across its path has only one way out, and how chains of blockers make a level hard.

• Working backwards from the exit

  Start from the goal, list what has to move, then play the plan forward. Two worked levels, every move shown.

• Par, stars and hints

  Why par is the shortest solution and not just a solution, how the game proves it, and how to spend a hint well.

The idea in one minute

The lot is six squares by six. Cars take two squares, trucks and buses three. A vehicle slides only along its own length, as far as it likes through empty squares, and that is one move. The level ends when the hero reaches the gap in the right-hand curb.

Most of a jam does not matter. Here is level 1, with the hero’s way out shaded:

1. Only vehicle D is in the hero’s path, so D has to leave it.
2. D is vertical, so it can only go up or down. Down is closed: it would need the square where truck G stands, and G is wedged between F and the curb and cannot slide at all.
3. Up is open once the square above D is free. Truck C is parked there, and C has room to slide one square left.
4. So the order is C, then D, then the hero: three moves, which is par. Four of the seven vehicles never move, and seeing which four is most of the skill.

The three guides take this further. They are written for a player who has played a few levels and wants to stop guessing.

Words used in the guide

Hero

The vehicle that has to leave. In every level of the game it is two squares long, stands in the third row from the top and faces the gap in the right-hand curb.

Lane

The row or column a vehicle slides along. Horizontal vehicles keep their row, vertical ones their column, for the whole level.

Blocker

A vehicle standing where another vehicle needs to go.

Chain

Blockers that are themselves blocked, one behind the other, until you reach a vehicle that can move at once.

Par

The fewest moves that solve the level. The solver proves it.

Squares

In these guides rows are counted from the top and columns from the left, starting at 1. Every drawing is built from a level of the game, and its number is given.

Where to practise

The boards in the guides are from the first tier, Learner, levels 1 to 40, so you will meet them early. You can read the guides in any order, but the second builds on the first. For the rules, the stars and the tiers, How to play is the reference.