Free printable logic puzzles
Each pack is a PDF of three or four pages that you can print at home. The first page explains the rules, the puzzles run from easy to expert, and the solutions are on the last page.
Puzzles invented at Prism Puzzles
Tridoku and Snowflake Sudoku have appeared in newspapers through King Features Weekly for over 15 years. Number Kingdoms is the newest of the three.
6 × 6 sudoku variants
Small sudoku puzzles that use the numbers 1 to 6. Each one takes a few minutes, and every puzzle can be solved by logic alone.
The books
The Prism Puzzles books are sold on Amazon. Each one begins with the rules and the solving strategies. Free online solvers are available for selected books.