Killer Sudoku players already know why cage totals are useful: a sum turns several open cells into a constrained combination. PUZRU keeps that arithmetic instinct but removes the 3×3 box rule and reduces the symbol set to 1–6 on a 6×6 grid.
What transfers immediately
Extreme sums, candidate combinations, row and column cross-checks and disciplined rescanning remain valuable. A cage can satisfy its total and still be impossible because one of its values conflicts with a row or column.
What is structurally different?
PUZRU is a Latin-square cage puzzle rather than Sudoku: no 3×3 boxes, only row and column uniqueness. Six values from each solved board also become fixed positions in the next Chain puzzle.
What is different as a game?
There is one current global puzzle. The first verified correct board becomes the Discoverer, then other correct boards can join during the contribution window before the shared 20-second transition.
What changes in practice?
Put the idea into practice
The fastest way to understand the interaction between row, column and cage constraints is to solve a board. Start in the 200-puzzle progressive Training Room, then enter the live world whenever you are ready to race for Discoverer.