Which Sudoku Variants Are Available on Stillgrid?

Updated

Stillgrid offers four sudoku variants: Classic, X-Sudoku, Jigsaw, and Killer. Each has its own rules page on the site, so you can read the rules before starting a puzzle. The site is mobile-first and requires JavaScript to play. The available material does not mention signup requirements or pricing, so treat access terms as unconfirmed until you open the site.

The four variants at a glance

Variant Defining rule What changes for the solver
Classic Standard 9×9 grid with 3×3 boxes Familiar rules; difficulty is the main variable
X-Sudoku Standard grid plus both main diagonals Diagonals must also contain 1–9 exactly once
Jigsaw Irregularly shaped regions instead of 3×3 boxes Region shapes vary by puzzle, so box logic does not transfer directly
Killer Cages with sum clues You combine sum arithmetic with normal sudoku constraints

Classic

This is the baseline: fill the grid so every row, column, and 3×3 box contains 1–9 once. If you already play sudoku elsewhere, this is the format you know. Stillgrid describes its difficulty as technique-graded, meaning puzzles are sorted by the solving techniques required rather than by how many clues are given. That matters if you want a puzzle that matches a specific technique you are practicing.

X-Sudoku

X-Sudoku adds one constraint to the classic grid: both long diagonals must also contain 1–9 exactly once. The practical effect is that cells on the diagonals carry extra restrictions, which can give you earlier placements and also create conflicts you would not see in Classic. If you are new to variants, this is usually the smallest step up from Classic because the grid layout stays the same.

Jigsaw

Jigsaw sudoku replaces the nine 3×3 boxes with nine irregular regions, often called jigsaw pieces. Each region still must contain 1–9 once, along with every row and column. Because region shapes differ from puzzle to puzzle, you cannot rely on memorized box patterns; you have to read the region outlines first. This variant rewards scanning region shapes before placing digits.

Killer

Killer sudoku adds cages: groups of cells marked with a target sum, and digits within a cage cannot repeat. You solve by combining those sums with row, column, and region constraints. The site also lists a Killer Sudoku Calculator, which suggests a tool for working with cage sums; the available material does not describe how it works, so check the page itself before relying on it.

How to choose a variant

  • New to sudoku or want a clean baseline: start with Classic.
  • Want a small twist without relearning the grid: try X-Sudoku.
  • Want to break reliance on box patterns: play Jigsaw.
  • Comfortable with arithmetic and want deeper deduction: try Killer.

A practical sequence is Classic first to confirm the interface, then X-Sudoku, then Jigsaw or Killer depending on whether you prefer shape-based or sum-based reasoning.

Other pages worth knowing

The site's page evidence also references a Daily Sudoku, an Archive, a Difficulty Grader, and an Evil Sudoku section. These are entry points rather than separate variants: the Daily and Archive give you puzzles to play, the Difficulty Grader relates to the technique-graded difficulty, and Evil Sudoku points to a harder tier. The material does not specify how each works, so open them directly if you want daily puzzles or a harder challenge.

Practical notes before you start

Stillgrid needs JavaScript enabled to play, so a browser with scripting blocked will show the page but not the puzzles. Each variant has an introduction page, which is the fastest way to confirm the exact rules the site uses, especially for Jigsaw region shapes and Killer cage rules.