How to Solve Hitori Puzzles
Find and shade all duplicate numbers in rows and columns, leaving only unique digits. No shaded cell may be adjacent to another, and unshaded cells must form a contiguous area.
How to Solve LITS Puzzles
Place one tetromino in each region such that all of them are orthogonally contiguous, no tetrominoes of the same type are adjacent, and no 2×2 area of cells is covered.
How to Solve Snake Puzzles
Use the clues to uncover the body of a snake, given the location of the head and tail. The body is a 1-cell wide path that travels only in orthogonal directions and may never touch itself, even diagonally.