How to solve unblock puzzles

"Unblock" puzzles are a whole family of games — sliding blocks, parking-lot jams, pin pullers, and tap-to-escape games like Fish Escape. They all share one shape: a crowded space, pieces that move only along their own axis, and a goal that is blocked by everything else. The pieces change, the shape doesn't, and that means the same handful of habits work across all of them. Here are the four we lean on most, with Fish Escape examples.

Habit 1 — Scan the edges before you tap anything

A fish can leave the tank only if every cell between its nose and the edge is empty. So the first question on any level is not "which fish do I like?" but "which fish are already free?" Walk around the border of the grid once, lane by lane, and note every fish whose path to the wall is clear right now. On early levels that is most of them. On a crowded late tank it might be one or two — and those are your only legal opening moves.

This sounds obvious, but the most common way to lose a heart is tapping a fish that looks free because its nose is near the edge, while a single rock or the tail of a long fish sits in the lane. Scanning the edge turns a guess into a fact.

Habit 2 — Count lanes, not fish

Beginners think in fish: "there are six fish, I need six taps." Experienced players think in lanes: each row and each column is a corridor, and every fish both uses one corridor to leave and occupies cells in corridors other fish need. A long fish lying across three columns is blocking three potential escape lanes at once, which makes it enormously valuable to remove early — if it can go.

Before your first tap, ask of each free fish: "how many other fish does this one unblock when it leaves?" Rank them. The free fish that unblocks the most is almost always the right first move, because it turns a tank with one legal move into a tank with three or four, and that extra choice is what keeps you out of deadlocks later.

Habit 3 — Respect the wake

Fish Escape adds a twist most unblock games don't have: when a fish swims out, it leaves a wake of seaweed along the lane it used, and that seaweed is a permanent wall for the rest of the level. (The order guide goes deep on this.) The practical consequence is that a lane you use is a lane you lose. So before freeing a fish, look at what else needs that lane. If two fish in the same row both face right, free the farther one first — its wake lies beyond the nearer fish and doesn't block it. Free the nearer one first and the farther fish is now swimming into seaweed.

The wake is also why "free the most-blocking fish first" is a rule of thumb rather than a law. Sometimes the most-blocking fish would lay its wake straight across the only exit for two others. When Habit 2 and Habit 3 disagree, Habit 3 wins: a blocked fish is a lost level, an unfreed fish is just a later move.

Habit 4 — Never tap on hope

Every lost heart in our playtesting came from the same moment: the player had found two or three safe moves, made them, and then — with the easy options gone — tapped the fish that "probably" could go rather than tracing its lane again. The board changes with every escape, so a lane that was blocked three taps ago may be open now, and a lane that was open may now be full of seaweed. Re-scan after every move. It takes two seconds and it is the single biggest difference between clearing a tank and restarting it.

If you genuinely cannot find a safe move, don't gamble. Use the Undo button to step back to the last point where you had choices, or spend a hint. A hint shows you the next correct fish; it doesn't solve the level for you, and watching which fish the hint picks is one of the fastest ways to internalise the lane logic.

Putting it together on a real tank

Imagine a 5×5 tank with four fish: a short fish at the top-left facing up, a long three-cell fish lying across the middle row facing left, a short fish under it facing down, and a short fish at the right edge facing right, with a rock sitting in the top row at column three.

1. Scan the edges. The top-left fish is free (its column above it is clear). The right-edge fish is free. The long middle fish is blocked by nothing to its left — also free. The bottom fish is free. Four legal moves.
2. Count lanes. The long fish occupies three columns, and the fish below it needs none of them — but if any other fish needed to swim vertically through the middle row, the long fish would be the key. Here nothing does, so it isn't urgent.
3. Respect the wake. The right-edge fish, when it leaves, lays seaweed across the rightmost cells of its row. Does anyone need that lane? No. The long fish, when it leaves, lays seaweed across the whole middle row to the left — and the fish facing down sits below the middle row, so it is unaffected. Safe.
4. Order: any order works on this tank, which is exactly what the scan tells you. On harder tanks the scan will leave you with one or two safe sequences, and that is the puzzle.

The habits don't make every level trivial — the later tanks are built so that even a careful player has to think — but they make every level fair. Once you're tracing lanes and watching wakes, you will never lose a heart to a surprise again, only to a plan that needed one more step of look-ahead. That kind of loss is the fun kind.

▶ Try it on level 1