How to play Harborline
Harborline is a logic puzzle about planning deliveries. Here is how a harbor works, how to plan a level from its docks backwards, and what each chapter adds.
The rules
Every harbor is a fixed puzzle with one goal: fill every dock with its exact load and leave nothing on the quay.
Combine
Two matching loads directly beside, above or below each other combine into the next larger load. Tap one, then the other, or drag one onto the other.
Choose the landing
The bigger load lands on the spot you picked second. The other spot is left as open water, and it stays empty for the rest of the level.
Deliver
Each dock, marked A to D, shows the load it needs. When that exact load lands on the dock, its flag goes up and the dock locks.
Clear the quay
A level is solved when every dock is filled and no other cargo is left. Nothing refills, nothing falls and there is no timer.
Nine kinds of cargo
Two of one kind always make one of the next. The ladder runs:
Parcel → Crate → Barrel → Chest → Container → Pallet → Cargo tower → Fuel tank → Freighter.
So a dock that wants a chest needs two barrels meeting on it — which means four crates, or eight parcels, routed to the right places first.
Planning tips
- 01Work backwards from each dock.The last move onto a dock combines two loads one size smaller, one of them already on the dock. Trace that back one size at a time and the harbor splits into a region for each dock.
- 02Direction is the whole game.The same pair combined the other way lands on the other spot. If that spot is cut off from its dock, the level can no longer be finished.
- 03Don't strand small cargo.A load with no matching neighbour it can ever reach will be left on the quay. Bring small loads together early, while the paths between them are still open.
- 04Use the warning.When the game is certain a dock can no longer be reached, it tells you and offers Undo or Restart. Undo is always free.
- 05Go back for a Clean Delivery.Solving without hints or undos earns a Clean Delivery. Replaying a cleared level can improve your record.
The 13 chapters
204 levels. Each was built backwards from its solved harbor, so every one ships with a verified solution.
| Chapter | Levels | Harbor | Docks | Moves |
|---|---|---|---|---|
| First Cargo | 1–16 | 4×4 | 2 | 4–9 |
| Dock C | 17–28 | 4×4 | 3 | 6–10 |
| Dock D | 29–40 | 4×4 | 4 | 8–12 |
| Deeper Loads | 41–60 | 4×4 | 2 | 8–13 |
| Wider Harbor | 61–80 | 5×5 | 2 | 12–18 |
| Three Currents | 81–92 | 5×5 | 3 | 12–18 |
| Four Currents | 93–104 | 5×5 | 4 | 16–21 |
| Uneven Loads | 105–126 | 5×5 | 2 | 16–23 |
| Full Harbor | 127–148 | 6×6 | 2 | 20–28 |
| Deep Channels | 149–160 | 6×6 | 3 | 20–28 |
| Cross Currents | 161–172 | 6×6 | 4 | 24–31 |
| Deep Water | 173–192 | 6×6 | 2 | 24–33 |
| Open Ocean | 193–204 | 7×7 | 4 | 30–40 |
Free vs Pro
Harborline has no ads, no energy and no paid retries.
| Feature | Free | Pro |
|---|---|---|
| Levels | 1–40 (all four docks) | All 204 |
| Hints, undo, restart | Unlimited | Unlimited |
| Harbor size | 4×4 | Up to 7×7 |
| Clean Delivery medals | Included | Included |
| Harbor themes | Harbor Day | Adds Tropic Bay, Sunset Pier and Night Port |
Levels unlock in order as you play, for everyone. Get Pro with the one-time Full Game Unlock, or with StackForge Play Pass while subscribed.
FAQ
Is every level solvable?
Yes. Each harbor was generated backwards from its solved position, and its solution is replayed before release.
Can I undo a move?
Yes, as often as you like. Undo and hints only cost you the Clean Delivery for that attempt.
Is there a timer or a move limit?
No. Take as long as you like; the only limit is the cargo on the quay.
Do I need an account?
No. The campaign plays offline. An internet connection is needed only for the Harbormasters rankings and optional account features.
What happened to Twoward?
Harborline is Twoward, redesigned. Cleared levels carry over. The store listing keeps the same app identity, so existing players keep their progress.