Welcome to RocketSudoku! This isn't your typical Sudoku game where you're left to figure things out alone. At any point during a game, you can discover what techniques are available on the board, learn how they work, and see them highlighted right on your puzzle.
Think of it as having a helpful guide available whenever you need it. The game shows you what techniques are available right now, explains how they work, and highlights them on the board so you can see exactly what's happening. The more you explore, the more naturally you'll start spotting these patterns yourself. Before you know it, you'll be finding Y-Wings and Skyscrapers like a pro!
Foundation Techniques
These are the building blocks. Master these first, and you'll have a solid foundation for everything else.
Naked Single
The "Obvious One"
When a cell has only one possible candidate left, that's your answer! It's the simplest technique, but also the most important. Every solved cell starts here—once you've eliminated everything else, what's left must be correct.
How to spot it: Look for cells with just one tiny number in the corner. That's your naked single, ready to go!
Hidden Single
The "Only Place It Can Go"
Sometimes a number can only go in one cell within a row, column, or 3×3 box, even though that cell has other candidates too. The number is "hidden" among other possibilities, but it's the only place in that unit where it can fit.
How to spot it: Scan each row, column, and box. If a number only appears as a candidate in one cell within that unit, you've found a hidden single!
Intermediate Techniques
Once you've got the basics down, these techniques will help you tackle tougher puzzles.
Pointing Pair or Triplet
The "Block Pointer"
When all the spots for a candidate in a 3×3 box line up in the same row or column, you can eliminate that candidate from the rest of that row or column outside the box. The box is basically "pointing" to where the number must go!
How to spot it: Look for a number that only appears in one row or column within a box. That number can't be anywhere else in that row or column.
Locked Candidate
The "Line Lock"
This is the reverse of a pointing pair! When a candidate is stuck in one row or column within a box, you can eliminate that candidate from the rest of the box. The row or column "locks" the candidate into that line.
How to spot it: Find a row or column where a number can only appear within one specific box. That number is locked to that box!
Naked Set
The "Group Elimination"
When a group of cells in a row, column, or box together only contain a specific set of candidates (like 2, 3, and 5), those numbers must go in those cells—and nowhere else in that unit. This lets you eliminate those candidates from other cells in the same unit.
How to spot it: Look for pairs, triplets, or quads of cells that share the same small set of candidates. Those numbers belong only to those cells!
Hidden Set
The "Secret Group"
A hidden set is like a naked set, but trickier to spot. A group of cells must contain a specific set of numbers (because those numbers appear nowhere else in the unit), even though those cells have other candidates too. Once you find it, you can eliminate the extra candidates from those cells.
How to spot it: Find a set of numbers that can only appear in a specific group of cells within a unit. Those cells form a hidden set!
Advanced Techniques
These patterns take a bit more careful observation, but they're super satisfying to spot and use.
Fish (X-Wing, Swordfish, Jellyfish)
The "Grid Pattern"
Fish patterns are elegant eliminations that work across multiple rows and columns. An X-Wing uses 2 rows and 2 columns, a Swordfish uses 3, and a Jellyfish uses 4. When a candidate appears in exactly the same columns across multiple rows (or vice versa), you can eliminate that candidate from the intersecting columns (or rows).
How to spot it: Look for a number that appears in the same columns across multiple rows, forming a rectangular pattern. That's your fish!
Finned X-Wing
The "Almost X-Wing"
Like an X-Wing, but with one extra candidate cell (the "fin") that breaks the perfect pattern. Even with the fin, you can still make eliminations within the fin's box.
How to spot it: Find an X-Wing pattern that's almost perfect, but has one extra candidate in one of the boxes. The fin still works for eliminations!
Skyscraper
The "Tower Pattern"
Imagine two rows (or columns) each with two candidates for the same number, arranged so they form an L-shape. The "roof" cells of this skyscraper can eliminate that candidate from any cell that sees both roof cells.
How to spot it: Look for two rows or columns with two candidates each, forming an L-shape. The cells at the ends of the L are your roof!
Two String Kite
The "Kite Pattern"
A pattern where a candidate appears in two cells of a row and two cells of a column, with one cell from each set sharing a box. The non-peer cells can eliminate the candidate from their shared peers.
How to spot it: Find a row and column that each have two candidates, with one cell from each sharing a box. The other cells form the kite!
Expert Techniques
These are the techniques that separate masters from advanced solvers. They need good pattern recognition and logical thinking.
Unique Rectangle
The "Deadly Pattern"
A special pattern with four cells forming a rectangle, where two cells share the same two candidates. To avoid having multiple valid solutions (which would break Sudoku's uniqueness rule), one of the rectangle's cells must contain a different candidate, allowing eliminations.
How to spot it: Find a rectangle of cells where two opposite corners share the same two candidates. That's your unique rectangle!
Y-Wing
The "Three-Cell Chain"
A powerful technique using three cells: a pivot with two candidates, and two "wings" that each share one candidate with the pivot and one candidate with each other. Any cell that sees both wings can eliminate their shared candidate.
How to spot it: Find a cell with two candidates, and two peer cells that each share one candidate with the pivot and one with each other. That's your Y-Wing!
XYZ-Wing
The "Three-Candidate Pivot"
Similar to a Y-Wing, but the pivot has three candidates instead of two. The pivot shares two candidates with one wing and two with another. Cells that see both wings can eliminate the shared candidate.
How to spot it: Find a cell with three candidates, and two wings that each share two candidates with the pivot. The wings eliminate their shared candidate!
W-Wing
The "Remote Pair Bridge"
A technique that uses a remote pair (two cells with the same two candidates that don't see each other) connected by a "bridge" of cells sharing a candidate. This lets you eliminate candidates in cells that see both remote pair cells.
How to spot it: Find two cells with the same two candidates that don't see each other, connected by a bridge of cells. That's your W-Wing!
WXYZ-Wing
The "Four-Candidate Master"
The most complex wing pattern, using a pivot with four candidates and multiple wings. This advanced technique lets you make eliminations through complex logical chains.
How to spot it: This is an expert-level pattern that needs careful analysis of candidate relationships across multiple cells.
XY-Chain
The "Chain Reaction"
A sequence of cells, each with exactly two candidates, where consecutive cells share one candidate. The chain connects two endpoints that share a candidate, letting you eliminate candidates in cells that see both endpoints.
How to spot it: Follow a chain of cells with two candidates each, where each cell shares a candidate with the next. The endpoints form your chain!
Your Technique Explorer
RocketSudoku is all about helping you learn and explore. Every technique you discover on the board is a chance to:
See it in action - Watch how the technique applies to your current puzzle
Understand the logic - Learn why the technique works
Practice recognition - Train your eye to spot these patterns yourself
The more you explore, the more naturally you'll start seeing these techniques in every puzzle. Before you know it, you'll be spotting Y-Wings and Skyscrapers like a pro!
