Extreme Sudoku Puzzles
(aka Giant, Monster or 25x25 Sudoku)
Extreme (aka Monster) Sudoku is a variant that typically has a 25x25 boxes making up the Sudoku grid instead of the standard 9x9. Extreme Sudoku uses the alphabet A-Y (all except Z) instead of the numbers 1-9. This makes for a massive board, but the fundamental game is unchanged.
Example of monster sudoku puzzle grid