How to play Sumrex
Sumrex is a calm daily logic puzzle. The board is 6×6, divided into six coloured regions, with a digit 1–9 in every cell. Your job: select exactly one cell in each row, each column, and each region, with no two selected cells adjacent (orthogonally or diagonally), so the six selected digits add up to today's target.
Each cell cycles on tap: empty → crossed → queen → empty. Use crosses to mark cells you've ruled out — for example, "no queen can have digit 9 if the target is 14, because the five smallest other digits already total 5 + 1 + 1 + 1 + 1 minimums per region". Crosses are scratch paper; only queens count toward the puzzle.
Press Check once you've placed six queens. If a rule is broken — two share a row, column,
or region, or two are adjacent — Sumrex tells you which rule, but never which queen. If the rules
are all met but the sum is off, you'll see by how much. Each Check counts toward the score on your
shareable result, so be deliberate. Reveal solution shows the answer with no penalty;
you'll still get a shareable, marked as revealed.
The twist
Pure-logic Queens-style puzzles (one per row, column, region, no adjacency) and pure-arithmetic sum puzzles both exist. Sumrex glues them together. Every day's puzzle has exactly one valid placement that also hits the target — and we verify, before shipping a puzzle, that it's solvable by deduction alone: no guessing, no backtracking, no "try this and see".
That changes how you play. Most of the deduction is about narrowing rows, columns, and regions until forced moves appear. The sum is a separate, complementary constraint: it caps the largest digit any single queen can hold, and once you've pinned a few queens it tells you exactly what budget the remaining ones must meet.
Strategy
- Use the sum to bound digits early. Every queen pulls from a different row. If today's target is 14 and the smallest digit available in five of the six rows is 1, the sixth queen can be at most 14 − 5 = 9. More usefully: if five rows have a row-minimum of 2, the sixth queen tops out at 4. Cross out everything above that cap in that row.
- Forced cells beat hopeful cells. Look for a row, column, or region where only one cell is still uncrossed. That cell must be a queen. Mark it, then propagate the adjacency rule — its eight neighbours are all crossed.
- Close on the budget. Once four or five queens are placed, the remaining budget (target minus the placed sum) often pins the last digits exactly. If two queens are left and the budget is 7, with row-minimums of 3 and 4 in those rows, both rows must take their minimums.
- Crosses are free. Every cross you place narrows the puzzle; mis-placed queens cost a Check. When in doubt, cross before you queen.
Worked example: the sum bound
Suppose today's target is 12. The grid contains digits 1–9. Six queens must total 12, no two sharing a row, column, or region, no two adjacent. Each queen sits in a distinct row, so each row contributes one digit to the sum. Take the minimum digit available in each row — call it the row-minimum. If the row-minimums of five of the six rows total 9, the sixth row's queen can be at most 12 − 9 = 3. Every cell in that row with a digit greater than 3 can be crossed immediately. That single sum-bound step often opens a forced move within seconds.
Frequently asked questions
How do I play Sumrex on mobile?
The whole game lives in a single 6×6 grid that fits comfortably on a 375px-wide screen. Tap a cell to cycle empty → crossed → queen → empty. Buttons sit beneath the grid in thumb reach.
What time does Sumrex reset?
Every puzzle is pinned to 00:00 UTC, so the whole world plays the same Sumrex on the same date.
Are Sumrex puzzles guaranteed solvable by pure logic?
Yes. Every shipped puzzle is generated, then verified by a logic solver that only uses forced-move deductions — no guessing, no search. If a candidate puzzle needs a guess, it's rejected before it reaches the queue.
Why can't I see my mistakes highlighted in green?
By design. Highlighting which queens are correct would partially solve the puzzle for you on every Check. Sumrex tells you when a rule is broken — adjacency, duplicate row, column, or region — and when the sum doesn't hit the target, but it never points at a specific queen.
More MinCalc games
Enjoyed Sumrex? Try Targle — the target is given, the six-character equation isn't, and you have six guesses to find it — or Quackle, an 8×8 pond-fill puzzle where every row, column, and pond holds exactly the right number of ducks.