Reddit reviews The Mammoth Book of New Sudoku (Mammoth Books)

Now don't look into variant sudoku puzzles (the black hole that it is). You'll feel like your inventing whole new strategies.

My favorite variant is Kropki Sudoku.

Edit will add some links.

1. Look in the file archive of this group https://www.facebook.com/groups/309473799153072/?ref=bookmarks lots of great original sudoku puzzles are poster there. - Great thing about this website is that it shows the authors website so you get way more sources.
   
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2. The World Puzzle Federation Grand Prix Puzzles go back a few years - the sudoku is a great source for original variants https://gp.worldpuzzle.org/content/sudoku-gp
   
   Example: https://gp.worldpuzzle.org/sites/default/files/Sudoku%20Round1.pdf
   
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3. Gareth Moores website https://www.puzzlemix.com/puzzles.php is a great source for the "Standard" variants.
   
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4. Richards Puzzles on logic masters website is a great series: https://logic-masters.de/Raetselportal/Benutzer/eingestellt.php?name=Richard
   
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5. [Edit] Adding this http://sudokucup.com/content/daily-league (forgot about this website - needs registration)
   
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6. Physical books I highly recommend DJAPE puzzles and Gareths Moors (Mammoth Book of New Sudoku)
   
   - https://www.amazon.ca/Puzzles-Dr-Djape-300-puzzles/dp/1979609950/ref=sr_1_2?keywords=djape&qid=1558058506&s=gateway&sr=8-2
   
   - https://www.amazon.ca/Mammoth-Book-New-Sudoku/dp/0762449365/ref=sr_1_fkmrnull_1?keywords=mammoth+book+of+new+sudoku&qid=1558058540&s=gateway&sr=8-1-fkmrnull
   
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7. Youtube: "Cracking the Cryptic" - Youtube channel which solves a variety of sudoku puzzles (Note: Am Patreon)
   
   \^ They really like Sandwich Sudoku (outside clues), but it looks like they are exploring more variants recently.
   
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   Adding https://krazydad.com/ to the list

I personally get most my Sudokus online instead of books as I like variants more and there's more variety there. I have a few books that have satisfy my enjoyment of variants.

The Mammoth Book Of New Sudoku by Gareth Moore If you want a lot of puzzles, this will probably suit you well. It has many common and uncommon variants. This one also has some overlapping grid puzzles.

Sudoku Mix #1 by Logic Masters India: Classic Sudoku and 5 variants. Nice handcrafted puzzles. This one has a slowly increasing difficulty per variant. Good for beginning new variants.

Mutant Sudoku by Thomas Snyder and Wei-Hwa Huang A large number of puzzles per variant from easy to very hard. Some common and some uncommon variants. Very nice book, but does go outside the normal sudoku books a lot. I wish there were more books like this.