Variant sudoku is sudoku, but there are more rules. It's generally not harder than regular sudoku once you learn the most common rules. I got into it from the Cracking the Cryptic YouTube channel. They have a Discord server as well. On the Discord, they post one easy variant puzzle a day (a "geniunely approachable sudoku", or "GAS"), which you can also find at the GAS website.

You can find variant sudokus on the Logic Masters Germany site. Most of them will link to the fantastic Sven's SudokuPad webapp for solving. For setting (making a puzzle), I recommend the SudokuMaker webapp.

Here is a talk I wrote on variant sudoku.

Some puzzles I've set

Click on a puzzle to start solving it.

Harpers Ferry Sudoku, 1/2/2024

• Normal sudoku rules apply.
• Adjacent digits on an orange Dutch Whispers line differ by at least four.
• Adjacent digits on a green German Whispers line differ by at least 5.
• Within cages, digits do not repeat and sum to the indicated value.
• Digits on the thermometer increase from the bulb end.
• The digit in the shaded square is even.

Domino Tree, 9/30/2023

• Normal sudoku rules apply.
• Digits separated by an “X” sum to 10.
• Digits separated by a “V” sum to 5.
• Digits separated by a white dot are consecutive.

Lascaux Cave, 9/29/2023

• Normal sudoku rules apply.
• Digits within cages sum to the number indicated.
• Digits along a thermometer increase from the bulb end.
• Thin lines form palindromes — that is, a digit some distance along a line from one end also appears the same distance along the line from the other end.