Gigantic 25x25 Sudoku Volume 1 - Spiffy Activity Books - 120 puzzles designed for seasoned Sudoku solvers who find the traditional 9x9 puzzles too easy. [front book cover]
Gigantic 25x25 Sudoku Volume 2 - Spiffy Activity Books - 100 puzzles designed for seasoned Sudoku solvers who find the traditional 9x9 puzzles too easy. [front book cover]

new activity books coming soon