Traffic Escape

How to play

Drag any vehicle along its own line, with a mouse or a finger. It snaps to whole squares and stops at whatever is in the way. With a keyboard, Tab to a vehicle and use the arrow keys.

Your car is the teal one, and it carries an arrow. Get it to the gap in the right-hand wall and you are out.

Nothing turns. A vehicle lying across the yard only ever moves left and right; one lying up the yard only ever moves up and down. That single constraint is the whole puzzle.

Rules and controls

• Every vehicle is two or three squares long.
• A vehicle only ever slides along its own line — nothing turns.
• Vehicles cannot overlap, cannot pass through each other, and cannot leave the yard.
• One continuous slide is one move, however far it goes. Three squares in one push costs one move, not three.
• You finish when your car reaches the gap in the wall.
• Undo and redo as much as you like — U and R, or the buttons.

Modes

• Starter — A lighter yard and a short way out. The place to begin.
• Standard — A full yard where the way out takes some working out.
• Expert — A packed yard and a long chain of moves before anything gives.
• Optimal-move challenge — You are told the fewest moves that exist. Match it — every wasted shuffle counts.
• Daily Jam — One yard, the same for everybody, seeded by the UTC date.

Tips

• Work backwards from your car. Find what is blocking it, then what is blocking that — the chain is usually short and almost always forced.
• Lorries are the difficulty. Three squares need three free squares to move at all, so shift them while there is still room.
• A vehicle you have moved out of the way can still be in the way of the next one. Think about where things end up, not just where they leave.
• The exit row fills up last. Anything you park on it has to come off again before your car can pass.
• If a yard looks stuck, it is not — every yard here has a way out. Undo costs nothing.

Privacy and local play

Everything runs in your browser. Your current yard, your settings and your best runs are kept on this device only, and the button under the board clears them without touching any other Zerdly tool. No account, no sign-in, and nothing about your play leaves the machine you are on.

Questions

Why does sliding a lorry three squares only count as one move?

Because a move here is one continuous slide, however far it travels. That is the rule the whole route counts in — the timer, your best runs and the best-possible number all use it — so nudging a vehicle one square at a time costs exactly the same as pushing it the whole way in one go. It is worth knowing before you try to beat a score.

Can I turn a vehicle?

No, and nothing else can either. A vehicle lying across the yard only ever moves left and right; one lying up the yard only ever moves up and down. That constraint is the whole puzzle — everything else follows from vehicles being permanently stuck on their own line.

Can a vehicle slide past another one?

No. Every square it passes through has to be empty, so a vehicle stops at the first thing in its way. Dropping it beyond an obstruction does not work either — the route checks the whole path, not just where you let go.

What is the best-possible number?

The fewest moves that exist for that yard. It is found by searching every position the yard can reach, so it is exact rather than an estimate, and it cannot be beaten. Matching it is the point of the optimal-move challenge.

Why is the best-possible number hidden while I play?

Because being told the answer takes fourteen moves before you start turns “find a way out” into “find the best way out”, which is a different and much harder game than the ordinary presets promise. You see it the moment you escape, and throughout the optimal-move challenge, where it is the objective rather than pressure.

How is the optimal-move challenge different from Standard?

It is the same size of yard and the same difficulty band — what changes is what you are asked to do. In Standard, shuffling vehicles around while you think costs you nothing. In the challenge you are given the fewest moves that exist and asked to match it, so every wasted slide counts. Its records are kept separately, because a move count from a run where shuffling was free is not comparable with one where it was not.

Are all the yards solvable?

Every one, and this is checked rather than assumed. A yard is built by starting from a solved layout and sliding away from it, so a way back always exists; then the whole reachable state space is searched to work out exactly how far from the exit the starting position is. A yard that could not be measured is discarded rather than shipped with a guess.

Does the hint ever guess?

No. It searches from the position you are actually in and offers the first move of a shortest remaining solution, and it tells you how many moves are left from there. It is worked out fresh each time, so it can never be advice about a position you have already undone.

What do the difficulty names mean?

A band is measured by solving the yard rather than attached to it by the generator, and it counts moves rather than squares. Starter yards are a few moves from the exit, Standard needs a chain of them, and Expert takes a long sequence before anything gives. The cuts differ slightly by size, because a busier yard can hold a deeper position.

Is anything sent to a server?

No. The generator, the solver, the hints, the sounds and your progress all run in your browser. There is no account, and clearing this game’s data leaves every other Zerdly tool untouched.

Related interactives

• Codebreaker — deduction against a hidden answer, and one of §8.29’s own suggestions.
• Box Push — the other sliding puzzle, where what you move cannot come back.
• 2048 — sliding tiles, with the board pushing back.
• Bridges — join the islands into one network.