Extreme Sudoku Online
Extreme sudoku is made for experienced players who find regular hard puzzles too easy. Fish patterns alone are not enough here. The puzzles require wing techniques, simple coloring, and plenty of patience. All puzzles are free and played right in your browser.
As on all our levels, every puzzle is verified by the solving engine: there is exactly one solution, and logic alone will always find it. The difference is that the chains of reasoning grow longer, and the patterns become 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 the puzzle to stand still for long stretches. That is normal at this level. The key is to switch strategies when one technique has nothing more to give: go 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 are regulars on extreme puzzles. Each technique has its own page with interactive examples that show you the pattern step by step.