Extreme Sudoku Online
Extreme Sudoku is designed for experienced players who find regular hard puzzles too easy. Fish patterns alone are not enough here: these puzzles require wing techniques, simple coloring and plenty of patience. Every puzzle is free to play in your browser.
As with every level, each puzzle is verified by our solving engine to ensure it has exactly one solution that can be found using logic alone. At this level, the chains of reasoning are longer and the patterns are rarer.
What you will encounter at the extreme level
The typical key moves are XY-Wing and XYZ-Wing, where a pivot cell and two wings together force eliminations. The Jellyfish extends the fish patterns to four lines, and simple coloring lets you follow a chain of cells for a single digit and expose contradictions.
Expect to make no progress for long stretches. That is normal at this level. The key is to switch strategies when one technique yields nothing more: move from fish to wings, from wings to simple coloring, and back again.
How to train your skills
The most effective training is to study the patterns in isolation before you hunt for them in real puzzles. Our technique pages show each pattern with interactive examples, so you know exactly what you are looking for.
Use the sudoku solver as a training partner: enter the puzzle you are stuck on and see which technique unlocks the situation. Over time you will recognize the situations yourself, and then you are ready for the brutal level.
Techniques you need at this level
These techniques appear regularly in extreme puzzles. Each has its own page with interactive, step-by-step examples of the pattern.