Water Sort is a calm logic puzzle: colored liquid is mixed up across a row of glass tubes, and your job is to pour it back and forth until every tube holds just one color. There is no timer pressure to win, but every pour counts, and the later levels need real planning.
The rules
Each tube holds four units of liquid, stacked in colored layers.
Tap a tube to pick it up, then tap another tube to pour into it. You can also drag from one tube to the other.
Only the top color pours. All of that color sitting together on top goes at once, as much as fits in the other tube.
You can pour into an empty tube, or onto the same color. You cannot pour one color onto another.
The level is solved when every tube is either empty or full of a single color.
Levels and difficulty
There are 200 levels. The first ones use three colors and five tubes; new colors are added as you go, up to twelve colors in fourteen tubes. Every level always deals the same puzzle, and every one has been checked by a solver to make sure it can be finished.
Clearing a level unlocks the next one. Your best time and fewest pours are saved for each level, and you can replay any level you have reached from the Levels list.
Tips for planning pours
Treat empty tubes as precious. Pouring into one is often the only way to uncover a buried color, so do not fill them with something you will just have to move again.
Look for colors that are already on top of two tubes: combining them frees space and often finishes a tube.
Before pouring, check what the move uncovers underneath. A pour that reveals a color with somewhere to go is better than one that exposes a dead end.
Work toward finishing one tube at a time. A full tube of one color is out of the way for good.
If a tube is nearly sorted with one stray unit on the bottom, it is usually better to empty it completely than to build on top of the stray color.
Getting unstuck
Undo takes back pours one at a time, as many as you like, so you can explore freely.
Once per level you can add an extra empty tube, which makes most tight spots easy to escape.
Hint shows a pour that leads to a solve. If there is no way to finish from where you are, it tells you to undo instead.
If no pour is possible at all, the game lets you know so you can undo or restart.
Scoring and accessibility
The clock starts with your first pour. Each cleared level scores 100 points per color, with a bonus for finishing without the extra tube and another for finishing without hints.
Every color has its own symbol, such as a heart, star or moon, printed on the liquid, so you never need to tell colors apart by shade alone. On a computer you can play with the keyboard: arrow keys and Space, or the number keys, to pick tubes.