Aquarium

What is Aquarium?

Aquarium is a logic puzzle played on a grid split into tanks. Glass walls divide the board into tanks of every shape, and you fill cells with water. Water in a tank settles the way real water does: it fills from the tank's bottom row up, one whole row of the tank at a time, so a tank can stay dry, fill part of the way or fill to the brim, but it never holds water above a dry row. The numbers along the top and the left of the board say how many cells of each column and each row hold water.

Every board has exactly one answer, and it can always be reached by reasoning, never by guessing. Boards come in three sizes, 6 by 6, 8 by 8 and 10 by 10, and a new board, the same for everyone, arrives every day.

How to play

Tap a cell to pour water into its tank up to that cell's row.

• Filling. A tap on an empty cell fills its tank from the bottom up to that cell's row, straight through any crosses on the way.
• Lowering. A tap on a cell with water lowers the water to just under its row, and that row of the tank gets crosses.
• Crosses. A cross is only your note that a cell stays dry. Tap a cross to clear the crosses of its row, drag across cells to cross out several at once, and once a row or column holds all its water, tap its number to cross out the rest of it.
• Numbers. A number dims when its line holds exactly that much water, and turns red when the line holds more, or can no longer reach it.
• Undo. Undo takes back your last change, a whole drag at a time.
• Score. Your score is the time to fill the board, plus 30 seconds for every hint. Every board size has its own leaderboard.

Strategy tips

1. Start with the extremes. A 0 keeps its whole line dry, and a number as big as its line fills every cell of it. Water settles, so a dry cell keeps its tank dry from that row up, and a cell of water fills its tank from that row down.
2. Think in rows of a tank. Inside one tank a row is all water or all dry, so a tank three cells wide can never fill in a row that needs only two more. The widths of the tanks that fill a row must add up to its number exactly.
3. The rest of the line is not enough. If the other cells of a row cannot make its number on their own, the tank that is left must fill in that row, and everything under it fills too.
4. Columns measure height. A tank running down a column puts one more cell of water in it for every row it fills there, so what the rest of the column leaves over caps how high that tank can fill.
5. Read two rows together. On the large boards, a tank that fills the upper of two rows always fills the lower one too. Weighing the two rows together often settles a tank that neither row settles alone.

FAQ

Is Aquarium free to play?

Yes. Like every game on Play, it runs free in your browser, with no download and no account needed.

Does every tank have to hold some water?

No. A tank can stay completely dry, fill part of the way from its bottom row, or fill to the brim. It never holds water above a dry row.

What does a hint do?

It fixes a wrong mark first if there is one; otherwise it fills what the next step of logic finds from the marks on the board, crosses out the cells that step knows stay dry, and the line under the board says which rule it used. Each hint adds 30 seconds to your time.

What is today's aquarium?

Every day everyone plays the same medium 8 by 8 board, so times compare directly on the leaderboard.

How is my score counted?

Your score is the time from the first look at the board to the last drop of water, plus 30 seconds for every hint. Lower is better.