Every filled thermometer in Thermometers Puzzle must be a continuous prefix from its bulb to its tip, every row clue (3, 2, 3, 1) and every column clue (2, 2, 2, 3) must be matched exactly, and the six-action keyboard solution on cells 1, 3, 6, 9, 11, and 12 is the disclosed route to a 940-point score. A player who treats the puzzle like Thermo Sudoku, who marks a floating tip, or who lets a single row exceed its total is one move away from breaking the solve. Each of those failures shares a single fix: read the row and column clues first, choose a thermometer whose bulb still sits on an empty cell, set the level as one integer, and stop the instant both line totals become exact. The fixed four-by-four board at Therometers Puzzle is built so that the eight solution levels (2, 1, 0, 2, 1, 2, 1, 0) sum to nine filled cells, and the same six Space actions the keyboard walkthrough uses are the cheapest path to 940.
The Three Mistake Categories in Thermometers Puzzle
Most failed solves collapse into one of three patterns, and recognising the pattern is what lets a player stop it before it costs a turn. The first pattern is the gap. A gap appears the moment a thermometer shows a filled tip with an empty cell behind it, which the rule set explicitly rejects because every filled path must be one continuous prefix from the bulb. The second pattern is the row overfill. A row overfill appears the moment the sum of filled cells in a row crosses its clue value, and the solver reports the line as a contradiction until a level is lowered. The third pattern is the Thermo Sudoku reflex, where a player reaches for digit ordering, consecutive jumps, or a 1-to-9 range. None of those tools apply here, because the rule set is about counting filled cells, not about values along the path.
Two smaller traps hide inside those three patterns. The first is treating Enter marks as fluid, when in fact Enter only writes a private reasoning note on an unfilled cell. The second is pressing Space on every segment of a path, which can stack a level past the clue. Both traps are easy to set up and both are reversed with one Space press because the interface rebuilds the filled-cell set from the declared levels after every action. A short read of the fluid-gap explainer and the completely-empty explainer covers the two largest confusion points without leaving the same tool family.
How the 4x4 Board and Eight Thermometers Are Built
The disclosed 4x4 grid is partitioned into exactly eight thermometers, and every thermometer is a two-cell path with a bulb on one end and a tip on the other. Because eight paths of two cells cover all sixteen grid cells, every cell belongs to one and only one thermometer, and the bulb and tip of each path are orthogonally adjacent. The path shape, clue values, fluid levels, controls, and score are fixed product choices on this board, so the layout does not rotate or randomise between visits. The maintained rule reference on Puzzle Thermometers and the cross-checked bulb-first behaviour on Puzzle Genius confirm the same no-gap, line-total, prefix-length behaviour that the on-screen solver enforces.
The partition has a useful side effect for mistake spotting. Because every cell is owned by exactly one thermometer, a floating tip can be located the moment it appears, and a row that exceeds its clue can be narrowed to the cell that pushed it over. The board is rendered as a responsive semantic CSS grid rather than a canvas, and every cell announces its position, bulb or tip role, fill state, and mark state to assistive technology, so the mistake a player is about to make is almost always visible on the cell itself before the Space press lands.
Set a Level With the Keyboard Without Creating a Gap
The keyboard flow is short, and each step is built so a wrong press either does nothing or actively reduces the level instead of pushing it past a clue. Mouse and touch users get the same logic through click and the context-menu gesture.
- Use the arrow keys to move the selection to a bulb or to a tip. The current cell highlights, and the role of the cell (bulb, tip, or middle) is announced.
- Press Space on a bulb or a tip to set that thermometer's level through the selected segment. The fluid fills from the bulb outward, with no empty cell between the bulb and the new tip.
- If the selected segment is already filled, press Space to lower the level to the segment immediately before it. This is the natural undo for a too-high level and never creates a gap.
- Press Enter only when a private empty-mark note is wanted. The note is placed or removed on an unfilled cell and is never treated as fluid by the validator.
- Watch the row and column totals update after every action. Stop the moment both totals land on the clue, because the score formula rewards fewer level actions and any extra press lowers the final score by ten points.
The same five-step flow works on a touch device, where a tap on a bulb or tip sets the level through that segment and the context-menu gesture places an empty mark. Validation rebuilds the filled-cell set from the declared levels after every action, so a level past the tip is rejected and a level that pushes a row past its clue is reported as a contradiction on the same action.
Read Row and Column Clues Before You Set Anything
Row and column clues are the only numeric targets the solver cares about, and they are the fastest way to catch a mistake before it costs a turn. The clues on this board are fixed and visible at the top of every row and the left of every column. A row whose clue is 1 has room for one filled cell, and a column whose clue is 3 has room for three.
| Line | Position | Exact Filled Cells Required |
|---|---|---|
| Row clue | Top to bottom | 3, 2, 3, 1 |
| Column clue | Left to right | 2, 2, 2, 3 |
| Total filled cells | Across all 16 cells | 9 (sum of solution levels) |
The row whose clue is 1 is the single most useful place to start, because any thermometer that places a filled cell in that row must end its fill exactly there. A common mistake is to treat the row clue as a maximum rather than an exact total, and the result is a row that overruns its clue by a single cell. The solver reports that overrun as a contradiction, and the only way out is to lower the level on the thermometer that pushed the row over. The column clue of 3 on the rightmost column is the second useful target, because filling it exactly usually sets the rest of the line totals in the same move.
An underfilled line is not a mistake. It simply means the solve is not complete yet, and the next legal level increase may close it. The validation layer only blocks level values that are negative, past the tip, or that push a line past its clue, so an underfilled board is always still playable and a level can still be raised.
Walk the Six-Action 940-Point Keyboard Route
The disclosed keyboard completion is six Space actions on cells 1, 3, 6, 9, 11, and 12, and each of those cells is a bulb or tip on one of the eight thermometers. The six actions set the level vector 2, 1, 0, 2, 1, 2, 1, 0 in path order, and the two zero entries leave two thermometers completely empty. The arithmetic is visible on the page: 2 + 1 + 0 + 2 + 1 + 2 + 1 + 0 = 9 filled cells, and 9 filled cells is exactly what the row and column clues of 3, 2, 3, 1 and 2, 2, 2, 3 must add up to. Because every level is a prefix length, the solution never contains a floating tip or a gap behind the fluid.
The score is a direct read of the action count. The disclosed formula is score = max(0, 1000 − 10 × level actions), so the six-action route yields score = max(0, 1000 − 10 × 6) = max(0, 1000 − 60) = 940. Any extra Space press on an already-correct thermometer lowers the level by one segment and the score by another ten points, so each extra press directly reduces the final score. A clean solve at 940 matches the score reached by the product's six-action disclosed solution.
How Validation, Restart, and the Boss Key React
Validation runs on every action, and it is the layer that prevents most mistakes from sticking. A level below zero is rejected, a level past the tip is rejected, and a level array with the wrong number of thermometers is rejected. A row or column that exceeds its clue is reported as a contradiction, and the next step is to lower the level on the thermometer that pushed the line over. A row or column that is still under its clue remains playable, because another legal level increase may complete it. The same rebuild also re-renders every row and column total on the screen, so a player can spot an overfill in the same instant it is reported.
Restart is the cleanest recovery when a mistake has already cascaded. Pressing Restart restores all eight empty levels, clears every Enter mark, resets the cursor to the starting cell, resets the score to 1000, and removes any contradiction flag. A completed best score may be saved only in the browser's localStorage, so it survives a Restart on the same device and browser but is not shared across machines. Double-press Escape to display the shared simulated spreadsheet boss cover, and press Escape twice more to return to the board without losing the in-progress state. The interface ships no audio, no timer, no random API, and no account requirement, so the only inputs that can introduce a mistake are the level choices themselves.