Water sort puzzle tips: how to solve the hard levels

Water sort, color sort, ball sort, bottle sort: the names change and the puzzle does not. Tubes hold layers of color. You pour from tube to tube until each tube holds a single color.

The early levels solve themselves. Then, somewhere past level fifty, you hit one that does not. It is rarely about difficulty. Hard levels are lost early, by one pour that spent the space you needed later. Here is how to avoid that.

The rule, exactly

Most versions share the same rule, and the small details matter:

• You can pour only the top color of a tube.
• It goes into an empty tube, or onto the same color if there is room.
• A pour moves as many layers of that color as fit. Whatever does not fit stays behind.
• A tube full of one color is done. In many games it gets a cap and leaves play.

Most levels deal a number of colors, four layers each, into the same number of full tubes plus two empty ones. Those two empty tubes are your whole working space. Everything below follows from that.

Treat empty tubes as your budget

An empty tube is the only place where any color can go. Pour a single layer into it and it now accepts only that color. You have turned a universal tool into a specific one.

So before you fill an empty tube, ask what it buys you. A good use uncovers a color that completes another tube, or empties a tube completely. A bad use moves one layer for the pleasure of moving it.

Six habits for hard levels

• Count before you pour. Look at every tube and find the colors that sit lowest, under the most layers. Those are the ones that will cost you. Plan to reach them early.
• Finish the nearly done color. If three layers of a color are already together, completing it frees a whole tube. A fresh empty tube is worth more than any other single pour.
• Read one layer deeper. The top color tells you where you can pour. The color under it tells you what that pour will uncover. Prefer pours that uncover something useful.
• Pour onto the deeper stack. When two tubes show the same top color, pour onto the one with more of that color underneath, so the run grows instead of splitting.
• Be careful with partial pours. A partial pour leaves a layer behind. Sometimes that is exactly right. Often it splits a color across two tubes that you will have to join again later.
• Empty a tube, then decide. A tube emptied completely is as good as an extra tube. If you can empty one in two moves, that is usually the best plan on the board.

When you are stuck

Most games tell you when no pour is left. Before you restart, undo back to the last move where an empty tube was still empty. That is almost always where the level went wrong.

If your game limits undo, charges for it or puts it behind an ad, restarting is often the cheaper option. Note which color you buried, and change your first two or three pours.

About solvers and impossible levels

Search for this puzzle and you will find water sort solvers: tools that take a level and return the shortest list of pours. They work because the puzzle is small. With four layers and around a dozen tubes, a computer can check every reachable position.

That also answers whether a level can be impossible. A randomly dealt level can be unsolvable unless the game checks it before it ships. Some games do and some do not. If one level has beaten you for a week, it is fair to wonder.

The extra tube, and other hooks

The standard way this genre makes money is the extra tube. Stuck? Watch an ad, or pay, and get one more empty tube. It works, because one extra empty tube solves almost any level. That is also why it is worth noticing: a level built to sell you a tube is tuned so that you need one.

Other common hooks are an ad after every level, a small number of undos with more for a video, and hint coins. None of these is wrong in itself. All of them are worth checking before you install. The ads and in-app purchases labels on the store page are the first place to look, and our guide to finding games without ads covers the rest.

Our color sort game

Hopvera's color sort game is called Glassful. It is in development and not in the store yet.

It plays by the exact rule above: four layers per tube, two empty tubes, and a pour moves as many layers as fit. Every one of its 1,000 levels is checked by a solver before it ships, so a solution always exists. Undo is free and unlimited, all the way back to the start, so there is no fail state. Every color also carries its own symbol, so you can sort by shape alone. The first release has no ads, no purchases and no extra tube to buy, and it works offline.

Telling colors apart is harder for more players than most puzzle games assume. We wrote about what makes a game color blind friendly. Feedback goes to Contact.