How to play Counterweight
A number puzzle about brass scales. Every puzzle has exactly one answer, and you never need to guess.
The two rules
1. Each number once. Fill the board with weights 1 to N (5 or 6). Each number appears once in every row and once in every column, like Sudoku.
2. Every beam balances. A row with a pivot under it is a beam. The small numbers under the cells are notches: how far each cell is from the pivot. A weight pushes with weight × notch. The left side must add up to the same as the right side. The cell right above the pivot does not tip the beam.
Example: a 5-cell beam with notches 2 1 · 1 2 (the middle cell sits on the pivot) holding 1 5 4 3 2.
left = 1×2 + 5×1 = 7 right = 3×1 + 2×2 = 7 → balanced (the 4 rests on the pivot)
The scale on the right of every row shows the left and right totals of the weights placed so far, and the beam tilts toward the heavier side. When a full beam balances, it glows.
New rules in later chapters
- Shelves (chapter 1): a row on a plank instead of a pivot only follows the once-per-row rule.
- Heavier side: an arrow says which side holds more total weight (just add the numbers), even though the beam balances.
- Anvils: an anvil hangs under a notch and adds its number there. Anvils let pivots sit off centre.
- Mobiles: a beam hangs by a chain from a notch of another beam. It still balances by itself, and its whole weight (21 on a 6×6 board, 15 on 5×5) pulls on the upper beam at that notch.
- Ember sums: a small glowing number in a cell's corner is the sum of the cells right above, below, left and right of it.
- Pans: a pan with a letter hangs under a notch and holds a copy of the weight in the cell marked with the same letter.
Tools
- Notes (✎): small pencil marks. Auto fills every number the row and column still allow.
- Undo, Erase, and a timer that pauses when you leave.
- Hints come in steps: first where to look (free), then the reason (one hint), then the weight itself.
- Keyboard: arrows move, 1-6 place, Backspace erases, N toggles notes, H opens a hint, Ctrl+Z undoes.
Checks and tries
Placing weights and notes is always free. When the board is full it checks itself; after that, press Check. A wrong check shows which beams or numbers break the rules and costs one of your 5 tries (one comes back every 30 minutes). Your first failed check on each level is free, and finishing a chapter refills your tries.
Stars
3 stars: solved on the first check with no hint. 2 stars: at most one failed check and one hint. 1 star: solved.
FAQ
Is there always exactly one answer?
Yes. Every puzzle is checked by our solver, which only uses steps a person can follow, and again by a brute-force search.
How is difficulty decided?
By the hardest step the solver needs: singles (Easy), beams with two empty cells, beams with three or four (Medium), larger beams (Hard), and two beams checked together (Expert).
What is Brass?
The game's coins. You earn Brass for new stars, the Daily, the Weekly, chests and achievements, and spend it on hints.
Do I need an account?
No. Progress is saved on this device. Sign in with an Ember ID to keep it in the cloud and play on several devices.
A tip for beams?
Start with beams that have only one or two empty cells: the gap between left and right tells you what they must add up to. On 6×6 boards all rows together always add up to a multiple of 21, which is why some beams need anvils.