Sudoku-4-YZ90 Thumbnail of a Sudoku-4-YZ90 puzzle.

Size:
4x4.
Elements:
Y, Z, 9, and 0.
Groups: Twelve total.
The 4 rows.
The 4 columns.
The 4 2x2 squares.
Instructions:
Precise details on group numbering.
Answer grids:
There are 288 answer grids,
(including all possible symetrically equivalent grids)

Puzzle Difficulty levels and Examples

Difficulty LevelLowHighExample
Easiest 2 2 Puzzle   ·   3-steps   ·   All-steps   ·   Solution grid
Easy 3 3 Puzzle   ·   3-steps   ·   All-steps   ·   Solution grid