If you're not sure about the rule set, try  Echo.
It's very easy and works well as a tutorial.
Normal sudoku rules apply.
The digit in the 1 position of a box indexes the 1's location in that box.
The digit in the 5 position of a box indexes the 5's location in that box.
The digit in the 9 position of a box indexes the 9's location in that box.
The positions within a box being:
If you enjoyed this puzzle, here are a few custom searches for  puzzles.
If you are inspired by any of my  puzzles, I invite you to set a puzzle featuring the ruleset. You can do so with or without the, "" moniker.Thanks for playing!
Lösungscode: The 6th row followed by the 7th column (no spaces)
am 16. Januar 2022, 10:50 Uhr von Elliott810
Very nice puzzle! Thx:)