Sudoku - 5700 original puzzles play online

5700 puzzles, all puzzles were created by the puzzle designer Naoki Inaba.
Beautiful puzzles (they are designed in various forms)
Cunning traps and original logic puzzles.
To improve logical thinking ability and memory.
Hybrid operation that allows you to choose both number-first and cell-first methods.
Sudoku Palace is the official sponsor of the Japanese national team for the World Sudoku Championship. *Held every year

8 levels of difficulty
Beginner
Novice
Intermediate
Advanced
Challenge
Challenge+
Ultimate challenge
Ultimate challenge+

Explanation on how to solve all the puzzles
Full House
Hidden Single
Naked Single
Locked Candidates
Hidden Pairs
Naked Pairs
Naked Triples
Hidden Triples
X-wing
Explanations of all puzzles using novice to advanced solving techniques, complete with diagrams (uses Coins)

Improved Hint function
In addition to showing the correct number, there will also be an explanation on why that number is the correct option.

Functions\tOn the settings page
You can write down candidates for each cell
You can set the background colour to your favorite colour
You can turn sound effects on or off
You can change the colour of the selected number to make it easier to spot
You can highlight rows, columns and blocks with different colours
You can adjust the placement of the numeric keypad
Auto-save
Start Over, Undo, and Reset buttons
Enter All Candidates and Delete All Candidates functions
Checker function to check if the number is correct (uses Coins)