2018-Jan: I've done a lot of behind-the-scenes work on the website this month (including removing all the ads). If you notice something has stopped working, please let me know, and I'll try to attend to it quickly.
Thank you for your patience and help! — Jim

Challenging Killer Sudoku, Volume 11

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.

Want to save some trees? You can download all 800 of these puzzles, in a more compact 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.

I've created a potentially useful one-sheet of candidate cage sets which makes it easier to eliminate numbers.

Problems printing puzzles? Try these work-arounds.

Out of challenging puzzles? Here's 800 more!.