Aquarium

• Regions
• Shading
• Numbers

Fill regions with water while respecting horizontal levels and outside clues.

1. Inside each aquarium the water level is horizontal: water in a cell means every lower cell of that aquarium is also water.
2. Outside clues give the exact number of water cells in each row and column.
3. Mark cells above the water level as air; every cell must be decided to finish.

• A filled cell forces every lower cell in the same tank to fill; cross-check that consequence against the edge totals.
• When a row or column reaches its clue, every remaining cell in that line is air.
• An aquarium can never contain water above a cell marked as air.
• Treat each aquarium as one container: choosing its water height resolves several cells.

We do not yet have a sufficiently verified account of this game’s origins. Rather than guess, we avoid attributing a date or creator without reliable evidence.

• When a row or column reaches its clue, every remaining cell in that line is air.
• An aquarium can never contain water above a cell marked as air.
• Treat each aquarium as one container: choosing its water height resolves several cells.

• Where should I begin? A filled cell forces every lower cell in the same tank to fill; cross-check that consequence against the edge totals.
• What makes this game different? Mark cells above the water level as air; every cell must be decided to finish.