Super-Tough Killer Sudoku, Volume 1

Each booklet contains a collection of eight different puzzles, 1-per-page, with a page of answers in the back. The booklets are ordered by ascending difficulty -- the puzzles in book 100 are much harder than the puzzles in book 1. All these puzzles have a single unique solution.

These puzzles are in PDF format and need the Adobe Acrobat Reader to view or print.

You can also download all 800 of these puzzles, in the 4-per-page format ( with hints and answers, with answers but no hints, or with neither hints nor answers).

Want to save even more trees? Try the online version of these puzzles.

Here's a handy cheat-sheet of candidate cage sets that makes it easier to eliminate numbers.

Problems printing puzzles? Try these work-arounds.

Have you ever tried to solve a puzzle without coffee? Let's keep the caffeine flowing and the puzzles free by donating $10 via Paypal.

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Prefer to donate by mail or venmo?  Here's how.

Out of super-tough puzzles? Here's 800 more!.