Dock Jam

What is Dock Jam?

Sliding block puzzles have been around for well over a century, and the traffic jam version is the one most people know: a grid packed with cars and trucks, and one car that has to get out. Dock Jam is our take on it, with boats instead of cars. The harbor is a 6 by 6 grid. The ferry sits in one of the middle rows, and you clear the level the moment it reaches the right edge.

It's free, it plays in your browser on a phone, tablet or computer, and there's nothing to install.

How to play

• Every boat can only slide along its own lane. Boats that lie sideways move left and right. Boats that point up and down move up and down. Nothing turns.
• Boats are two or three cells long and can't pass through each other.
• Drag a boat as far as it will go in one motion. One slide counts as one move, however far it travels.
• Get the ferry to the right edge of its row to clear the harbor.

Rocks

Some harbors have rocks. A rock fills one cell for the whole level, so lanes that cross it are shorter than they look.

Tides and sand

Tide harbors have patches of sand, and the tide flips with every move you make. At high tide the sand is underwater and boats glide over it. At low tide the sand blocks, and any boat that's sitting on sand is grounded until the water comes back. A pill above the board tells you which tide it is. If the next move you want needs the other tide, tap Wait to let the tide turn. Waiting counts as a move.

The gull

From level 6 on, a gull starts watching. If you sit still for about 16 seconds it circles the harbor for a few seconds, then swoops in and steals a move, which adds one to your count. Tap it while it's circling and it flies off.

Controls (phone and computer)

On a touch screen, drag boats with your finger. With a mouse, click and drag. You can also play with the keyboard:

Stars, par and helpers

Every harbor has a par, and in Dock Jam par is the true minimum. Our solver checked every possible position, so if you match par you've found the fewest moves there are. Stars are based on your move count, including any moves the gull steals:

• 3 stars: par plus a small margin (about 15 percent, at least one extra move).
• 2 stars: par plus about 60 percent (at least four extra moves).
• 1 star: any finish.

The win screen tells you how many moves 3 stars needed and what the best possible was. Undo is free and unlimited.

Hints and the crane

A hint highlights the next move of a shortest solution from where you are now. You start with 3. The crane lifts any boat except the ferry straight out of the harbor. It counts as a move and limits you to 2 stars on that try. You start with 1 crane. You earn more like this:

• +1 hint for your first win each day.
• +1 hint for a first 3-star finish on every third level.
• A gift crate every 5 new levels, worth +2 hints and +1 crane.

Harbors, daily puzzle and ferry colors

The 60 levels are split into four harbors of 15: Sunny Cove, Lighthouse Bay (where rocks start showing up), Tide Flats (where the tide starts turning) and Coral Point (everything at once). Every fifth level is a little easier, to give you a breather.

The Daily Harbor is the same puzzle for everyone each day, usually a crowded board with a dozen boats. It's scored out of 1,000: you lose 30 points per move over par and 200 for using the crane, down to a floor of 100. Play it daily to keep your streak alive, then check where you landed on the leaderboard.

Stars also unlock new paint for your ferry in the Paint Shop:

Unblock puzzle tips

• Work backward from the exit. Look at the cells between the ferry and the right edge. For each boat in the way, ask which direction it has to move and what is blocking that. Keep following the chain until you hit a boat that can move right now. That's usually your first move.
• Count space at the ends of lanes. A long upright boat in the ferry's row needs enough room above or below it to get completely out of the row. If one side doesn't have three free cells, it has to go the other way.
• Don't slide everything to the walls. Pushing boats as far as they'll go feels tidy, but it often seals a gap you need two moves later. Move a boat only as far as the plan needs.
• A long slide is still one move. When you're chasing par, look for moves that do two jobs at once, like clearing one lane and opening another.
• Plan tides in pairs. On tide levels the tide flips every move, so moves alternate between high and low. If a boat on sand needs to move, make sure you get to it on a high tide move, or you'll end up spending a Wait.
• Keep the gull honest. If you need a long think, tap the gull away when it shows up. On a 3-star attempt one stolen move can cost you a star.
• Use undo freely. It costs nothing, so try ideas. Save hints for when you truly can't see the chain.

Want another tidy puzzle afterward? Try Jelly Jars for color sorting or Firefly Paths for a connect the dots puzzle.

Questions