Sudoku is a popular, logic-based, combinatorial number-placement puzzle. The objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 subgrids (also called “boxes”, “blocks”, or “regions”) that compose the grid contain all of the digits from 1 to 9 exactly once.
The puzzle setter provides a partially completed grid, which for a well-posed puzzle has a single unique solution. Unlike math problems, solving a Sudoku puzzle requires no arithmetic skills; it relies purely on logical deduction.
Key Rules
- Rows: Every row must contain the numbers from 1 to 9, without repetitions.
- Columns: Every column must contain the numbers from 1 to 9, without repetitions.
- Subgrids (3x3 blocks): Each 3x3 block must contain the numbers from 1 to 9, without repetitions.
Features of This Sudoku App
Our modern Sudoku implementation offers a rich, user-friendly experience equipped with several advanced gameplay features:
1. Advanced Multiple Selection (Notes/Pencil Marks)
A standout feature of this app is the multiple selection in one cell capability.
- Candidate Noting: Players can toggle a “Notes” or “Pencil” mode allowing them to add multiple mini-numbers (candidates) inside a single cell.
- Strategic Deduction: This is essential for solving harder difficulties, as it allows players to track possible digits for a cell before committing to a final answer.
2. Diverse Difficulty Customization
Powered by a dedicated backend Python solver architecture, the app generates puzzles across multiple tiers of complexity:
- Easy: Ideal for beginners with plenty of starting clues.
- Medium: A balanced challenge.
- Hard: For seasoned players needing advanced logical tactics.
- Expert: For elite players, operating with the minimum number of clues required for a unique solution.
3. Smart Validation and Highlighting
- Automatically highlights conflicting numbers in red if a player inputs a digit that breaks the row, column, or subgrid rules.
- Highlights identical numbers across the entire board when a digit is selected, making it easier to scan missing spots.
4. Modern, Responsive Architecture
- The game is built using a modern Svelte frontend combined with Tailwind CSS, ensuring a buttery-smooth, responsive experience on both mobile and desktop.
- The puzzle generation API is highly scalable, ensuring instant loads with zero latency at the edge.
5. Guaranteed Unique Solutions
Every puzzle generated by the underlying backend guarantees exactly one valid solution, avoiding the frustration of ambiguous puzzle states.