What is Sumrex?
Sumrex is a placement puzzle that combines spatial logic with arithmetic. You place six rex on a 6 × 6 grid divided into colored regions, following standard placement rules plus one numerical constraint: the six covered numbers must sum to the day's target. One rex per row, one per column, one per region, none touching even diagonally, and the six numbers must hit the exact target. The game guarantees a unique solution with no guessing.
How to play Sumrex
Check the target above the grid. The six covered numbers must add up to it.
Tap a cell once to cross it out, twice to place a rex, and three times to clear it. Place six rex, with one in each row, column, and colored region. No two rex may touch, even at a corner.
Watch the sum counter as you place the rex, then tap Check to validate your solution.
Why the target changes the puzzle
Without the sum constraint, multiple valid placements would exist. The target narrows the search to the one arrangement that satisfies both placement rules and the arithmetic requirement. The interface shows a rex counter (0 / 6) and a sum counter, and the grid divides into six colored regions. Clear and Reveal solution buttons are available, along with a help page that offers three hints without spoiling the answer.
Tips for solving
The first tap crosses out a cell rather than placing a rex. Use this to eliminate numbers that cannot contribute to the target sum. A placed rex blocks its eight neighbors, including diagonals, so each placement constrains more than just its row and column. The target acts as a filter: several arrangements satisfy the spatial rules, only one hits the correct total. If stuck, check which regions or rows have fewer valid options and work from those constraints first.
Popular questions
What is a rex?
The piece you place on the grid. Six rex per puzzle, one per row, one per column, one per colored region, none touching.
Do I sometimes have to guess?
No. Each puzzle has a unique solution that can be reached through logic.
What should I do if I get stuck?
The help page offers three progressive hints. If you prefer to see the answer, tap Reveal solution.