How to Play Thermometers

Basic Rules

• 1.The grid contains thermometers with a bulb (rounded end) and a tip (other end).
• 2.Fill thermometers with mercury (red) starting from the bulb toward the tip.
• 3.Mercury must be continuous - no gaps allowed! If a cell is filled, all cells between it and the bulb must also be filled.
• 4.The numbers at the edge of the grid show how many cells should be filled in that row or column.
• 5.A thermometer can be completely empty, partially filled, or completely filled.

Controls

• ClickFill cell with mercury (red)
• Click againMark cell as empty (X) - use this when you know it must be empty
• Click againClear the cell (unknown state)
• Arrow keysNavigate between cells
• Space/EnterToggle current cell
• Ctrl+ZUndo last move
• Ctrl+YRedo

Strategy Tips

• 💡Start with 0 clues: If a row or column has 0, all cells in that line must be empty. Mark them with X.
• 💡Check maximum fills: If a clue equals the total thermometer cells in that row/column, all must be filled.
• 💡Use the continuity rule: If you fill a cell, you must fill all cells between it and the bulb.
• 💡Mark empty cells: If a cell can't be filled (would exceed a clue), mark it X. This helps deduce other cells.
• 💡Work both directions: Check both row and column clues for each thermometer to narrow down possibilities.

Visual Guide