Extremely Difficult Sudoku Puzzles

If Very Hard Sudoku Puzzles are no longer challenging enough, it’s time for the ultimate test of skill. Extremely Difficult Sudoku Puzzles take problem-solving to the highest level, where standard elimination techniques rarely suffice, and solutions require advanced analysis and strategic planning.

At this difficulty, puzzles provide even fewer clues and often demand multi-step reasoning before you can confidently place a number. This is a challenge for the most advanced players who want to push their logical skills to the limit.

On this page, you’ll find 2,000 of the most played Extremely Difficult Sudoku puzzles. Out of millions of available grids, these have been the top choices among players seeking the ultimate challenge. Each puzzle at this level demands in-depth analysis and advanced techniques to reach the correct solution. If you can solve these, it means you are ready for the highest level of Sudoku mastery.

What Makes the Extremely Difficult Level Stand Out?

• A minimal number of starting clues, meaning every decision is crucial.

• The necessity of using the most advanced logical techniques.

• Ideal for players seeking expert-level Sudoku challenges.

How to Solve Extremely Difficult Sudoku Puzzles?

At the Extremely Difficult Sudoku Puzzles level, standard elimination techniques are rarely effective, and solving the grid requires in-depth analysis of logical relationships between cells. While strategies from previous levels—such as Nishio, Almost Locked Sets, and Grouped X-Cycles—are still valuable, even more advanced techniques may be necessary to eliminate incorrect values in the most complex puzzles.

1. Using the “Chain Coloring” Method

The Chain Coloring technique helps eliminate incorrect candidates by tracking logical dependencies between connected cells. If two alternative values in a cell lead to a contradiction elsewhere in the chain, one must be correct, and the other must be eliminated. Follow these steps:

➡ Select a digit to analyze and find all the cells where it can appear.

➡ Assign two different “colors” to the two possible values and follow their logical relationships throughout the grid.

➡ If one color creates a scenario where the same number must appear twice in a row, column, or block, then that color is incorrect.

➡ Eliminate all candidates associated with the incorrect color and continue solving the puzzle.

Example:

If the number 7 can only appear in two locations in a column, and both are connected to other cells in a block, you can assign them different “colors” and analyze the consequences. If one color leads to a contradiction, then the other must be correct.

2. Applying the “2-String Kite” Method

The 2-String Kite technique is a variation of Skyscraper, allowing numbers to be eliminated when they are restricted to two possible positions in different rows or columns but share a common connecting point. Follow these steps:

➡ Identify two cells in different rows that contain the same number as a possible candidate.

➡ Check if these two cells are linked by a third cell in another column or row.

➡ If they are, eliminate that number from other locations in the shared row or column, helping to simplify the puzzle.

Example:

If 4 can only be placed in two locations in rows 3 and 7, and both are linked through a common column, then 4 can be eliminated from other cells in that column, making solving easier.

3. Using the “Kraken Fish” Method

Kraken Fish is one of the most advanced elimination techniques, allowing for simultaneous analysis of a digit’s possible placements across multiple rows and columns. This method helps uncover logical dependencies across the grid and eliminate incorrect values. Follow these steps:

➡ Identify a digit that can only appear in specific locations across multiple rows or columns.

➡ Analyze what happens if that digit is placed in each of those positions—does it force another number into a conflicting position?

➡ If placing the digit in any of the possible locations leads to an unsolvable situation, then it must be eliminated from certain cells.

Example:

If 9 can only be placed in specific cells in three different columns, but every possibility leads to a scenario where another number is forced into an invalid placement, then 9 must be eliminated from some of those cells, allowing for further progress in the puzzle.

At the Extremely Difficult Sudoku Puzzles level, multi-step logical analysis is essential for finding the correct values in complex grids. Techniques like Chain Coloring, 2-String Kite, and Kraken Fish help eliminate incorrect candidates, allowing for the resolution of even the most demanding puzzles.

What’s Next? Try Expert Sudoku Puzzles

If Extremely Difficult Sudoku has become too manageable, it’s time for the final step in the difficulty scale. Expert Sudoku Puzzles are designed for true masters of the game—requiring maximum concentration, deep deductive reasoning, and an expert-level understanding of logical structures.

Choose a puzzle and see if you can conquer this challenge!