The giant. Fill the 16×16 grid so every row, column and 4×4 box contains each value 1 through 16 exactly once — shown as digits 1–9 and letters A–G for the values above 9.
Rules
Click an empty cell, then click a symbol below (or type a digit 1–9 or a letter A–G) to fill it in.
Every row, every column, and every 4×4 box must contain each value 1–16 exactly once — a repeated value in that row, column or box is shown in red.
Arrow keys move the selected cell; Backspace, Delete or 0 clears it.
Fill in every cell correctly to solve the puzzle — pick a difficulty and press "New puzzle" any time for a fresh one.
Tips
Work one 4×4 box at a time rather than scanning the whole grid at once — it’s much easier to hold 16 values in mind for one box than for the full grid.