What is 16x16 Sudoku?
The only difference between a 16x16 Sudoku and a classic Sudoku is the number of cells. A 16x16 Sudoku has 16 rows and 16 columns. The resulting 256 cells are also divided into 16 blocks, each with 4x4 cells.
The numbers are, on this website, replaced by letters. This variant is sometimes also known as Alpha Doku. This is done because the letters are more distinguishable from each other than the numbers from 1 to 16.