Mini Killer Sudoku looks busy—dotted cages crossing block lines—but the rules are crisp. This guide states them without fluff, ties them to how ProPuz presents puzzles, and shows where beginners usually misread the board. If you want habits more than definitions, pair this page with our beginner tips.
The grid and the digit set
A Mini Killer puzzle is a 6×6 square. You place integers from 1 through 6 so that each number appears exactly once in every row, exactly once in every column, and exactly once in every 2×3 block. The six blocks partition the grid the same way Mini Sudoku does on ProPuz: two rows of three blocks across, each block holding six cells in a 2×3 rectangle.
That triple uniqueness—row, column, block—is the Sudoku half of the puzzle. It never goes away, even when cage arithmetic feels like the main event. Every fill you make must pass all three unit tests before you even ask whether the cage is happy.
Cages and sum clues
Overlaid on the grid are cages: groups of one or more cells outlined with dotted lines. One cell in each cage (typically the top-left of the group) displays a small number: the sum clue. The digits you eventually place in that cage must add up to exactly that total.
Cages can span multiple rows, columns, and blocks. A single cage might touch three different 2×3 regions. That overlap is why Mini Killer feels richer than plain Mini Sudoku: you are solving two constraint systems at once, not alternating between them.
No repeats inside a cage
This rule catches newcomers who know Killer Sudoku from newspapers but forget the detail under pressure: digits within a cage cannot repeat, even if repeating would still satisfy the sum. A two-cell cage labeled 10 cannot be {5, 5}—it must be {4, 6}. A three-cell cage summing to 8 cannot use 2 twice; legal triples on 1–6 use distinct digits only.
Cage uniqueness is independent of row uniqueness. Two 3s cannot sit in the same cage, but they also cannot sit in the same row—both rules apply simultaneously. When Check fails, ask which uniqueness broke first.
Empty-start play on ProPuz
Unlike many classic Sudoku formats, ProPuz Mini Killer typically shows an empty grid at the start. No digits are pre-filled as givens. All information arrives through cage labels and the implicit Sudoku structure. Your first placements come from combination logic—recognizing that a cage of sum 3 in two cells must be 1 and 2—and from eliminations as partial fills propagate.
Empty starts can feel like staring at a blank page. They are normal. Well-generated Mini Killer puzzles are designed to be uniquely solvable from cages alone. If you feel stuck, you have not finished reading the cage menus, not run out of puzzle.
Difficulty tiers: Easy through Expert
ProPuz offers Easy, Medium, Hard, and Expert Mini Killer boards. The grid size stays 6×6; difficulty changes cage layouts, combination depth, and how many constraints interact in a single cell. Easy puzzles lean on small cages with obvious pair menus. Expert boards demand longer combination chains and tighter bookkeeping.
Treat tier jumps as skill gates, not vanity labels. Master Easy with clean Check passes before chasing Expert combination catalogs. The rules sentence is identical at every tier; the scanning labor scales.
What counts as solved
A grid is solved when every cell holds a digit from 1 to 6, every row/column/block contains each digit once, every cage sums correctly, and no cage contains duplicate digits. Partial grids can look promising and still be illegal—a row may be perfect while a cage still wants a different pair.
On ProPuz, Check compares your entry against the stored solution for that puzzle. Play aims at the unique intended completion, not an alternate Latin square that happens to satisfy visible cages if one existed. Well-designed puzzles are generated to be uniquely solvable from the cage layout.
What Mini Killer is not
It is not KenKen with arbitrary operations: cages here always sum, never multiply or subtract. It is not Futoshiki: there are no inequality signs between neighbors. It is not full 9×9 Killer Sudoku: the digit range is 1–6, blocks are 2×3, and combination menus are smaller but still mandatory.
It is also not plain Mini Sudoku unless you ignore the cages. Playing Mini Sudoku habits on a Killer board—filling rows without sum checks—is the fastest route to a Check failure.
Worked micro-example (6×6 thinking)
Suppose a two-cell cage in the corner shows sum 3. Legal digits are 1 and 2 only. If one cell sits in row 1 and the other in row 2, row 1 cannot later host another 1 or 2 in those positions once you decide orientation—but you might not know orientation yet. Cross-check column and block constraints: if column 1 already forbids 2 in the top cell via another cage, the top cell must be 1 and the partner 2. That is the whole game in miniature: combine local sums with global Sudoku units.
If a cage of sum 11 spans two cells anywhere on the board, those cells are {5, 6} in some order—often an immediate placement once a row or block eliminates one option. Learn those forced pairs and the opening moves become visible within seconds.
Interface rules on ProPuz
Select a cell, type a digit 1–6, erase when needed, and move with clicks or arrows. Notes mode helps track candidates when three constraints intersect. Generate a new puzzle from the play sidebar when you want a fresh cage layout. Daily challenges freeze a shared puzzle per date and tier so friends can compare notes on the same board.
If Check reports an error, believe the checker and hunt the broken contract—duplicate in a block, wrong sum, or repeat inside a cage. Debating the interface rarely fixes a duplicated 4.
Glossary-style recap
Grid — 6×6. Digits — 1 through 6 each used once per unit. 2×3 block — one of six Sudoku regions. Cage — dotted outline with a sum clue. Cage uniqueness — no repeated digit inside a cage. Solution — complete legal grid matching ProPuz’s intended answer.
Memorize those terms and you can read almost any Mini Killer help page without getting lost in branding differences between sites.
Keep going
Rules are short; skill is scanning. Practice them on an Easy ProPuz grid, review how to play, study common mistakes, or follow a structured walkthrough in solve a 6×6 step-by-step. Return to the articles hub whenever you want the next guide in the series.