Sudoku vs Fillomino: Symbols, Regions, and Logic Compared

Sudoku uses fixed rows, columns, and boxes

Sudoku gives you the full geometry before you begin. Every row, every column, and every 3 by 3 box contains the same nine symbols exactly once. The challenge is determining the missing value of each cell. If a symbol already appears in a row, column, or box, it cannot appear again in that unit. More advanced deductions combine candidate restrictions across several cells. Shapedoku preserves these rules while replacing digits with colorful glowing shapes, which underlines an important point: Sudoku numbers do not represent quantities. The diamond is not greater than the circle, just as the digit 8 is not treated as a quantity during an ordinary Sudoku deduction. Each symbol is simply one member of a nine-item set. This fixed structure makes techniques highly reusable. Once you understand a pointing pair or an X-Wing, the same pattern can appear on thousands of different grids even though the clue arrangement changes.

Fillomino makes the numbers describe region size

Fillomino uses numbers in a very different way. The grid must be divided into orthogonally connected regions, and every cell in a region contains the same number. That number equals the total number of cells in the region. A region filled with 4 must therefore contain exactly four connected cells. Two separate regions of the same size cannot touch horizontally or vertically, although they may touch diagonally. Some numbers are given at the start and others are discovered as the regions take shape. If a clue 3 already has three connected 3 cells, that region is complete and every orthogonal neighboring cell outside it must be something other than 3. If two given 5 cells are close enough that they must belong to one region, you can search for ways to connect them while keeping the final region at exactly five cells. The puzzle therefore combines counting, connectivity, and boundary control rather than no-repeat placement.

Use capacity in Fillomino the way you use candidates in Sudoku

A useful comparison is to think of unfinished Fillomino regions as having capacity. A region marked 6 with four confirmed cells still needs exactly two more cells. If only two neighboring cells can legally extend it, both are forced into the region. If three possible cells remain, preserve all three possibilities until another region or boundary removes one. This is similar to candidate discipline in Sudoku: uncertainty is information, not a reason to guess. Another strong Fillomino deduction comes from preventing equal regions from touching. If a completed 2 region sits beside an unresolved cell, that cell cannot become part of a different 2 region touching it along an edge. Choose Sudoku when you prefer fixed units and symbol candidates. Choose Fillomino when you enjoy regions that expand, stop, and interact dynamically. Shapedoku is useful for practicing the first style with Notes and four difficulty levels. If the grouping aspect of Fillomino appeals to you, Mystic Sort offers a different calm grouping puzzle from SnailPixel, where glowing potion colors are poured until each container reaches color harmony. Google Play: [https://play.google.com/store/apps/details?id=com.snailpixel.mysticsort](https://play.google.com/store/apps/details?id=com.snailpixel.mysticsort).

• In Sudoku, numbers or shapes identify distinct symbols that cannot repeat inside a unit.
• In Fillomino, each number describes the exact size of its connected region.
• Use candidate elimination for Sudoku and remaining region capacity for Fillomino.
• Close a Fillomino region as soon as it reaches its required size.
• Prevent separate equal-sized Fillomino regions from touching orthogonally.
• Choose Sudoku for fixed-unit logic or Fillomino for region growth, counting, and connectivity.