Classic Hard Sudoku belongs to the eponymous category.
If you like Classic Hard Sudoku, check out these variations and family games: Easy Sudoku, Medium Sudoku, Expert Sudoku and Evil Sudoku, and others.
With in Solitaire games you keep your mind sharp while you relax – join thousands of people already play our solitaire games!
This page was last updated on 17 October 2025.
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Goal: Ensure that every row, column, and each of nine 3x3 sub-grids of a 9-by-9 grid contains the numbers one through nine, without any repetition.
Game complexity: Medium
Game rating – 4.8 on 3,270 likes
Welcome to in Solitaire – the best dark online Solitaire!
Hi there, I am Evgeny, the guy who created this game collection with the goal to create the ultimate Solitaire experience, so far we have 55 games.
All games here are free, no download or registration required. I update the platform almost daily, so check back often for new stuff. If you have any feedback or suggestions, send me a message at evgeny@krapivin.co.