Logic Masters Deutschland e.V.

Standard sudoku rules applies. Fill the grid with numbers from 1 to 9 so each digit occurs exactly once in every row, column and 3x3 box.

Four digits surrounded the circle increase or decrease clockwise.The number in the circle show the product of the biggest and smallest number around the circle.

All possible circle are given. In other words, places without a circle don't have the 4 clockwise increasing or decreasing digits.

f puzzle link

This puzzle is made by Old Miles from China in 2017.Hope you guess it right.

Some of you might know the type idea didn't come from Old Miles. But he change the rules bit by bit, creating a series of 8 puzzle. Solving one puzzle will always raises the question of what will come next. The rules became shorter (compared to the type bad C, which is the orginal ruleset). longer rules just made the puzzle a little bit harder.I really want to see a series with rules developed pace by pace, not just add killer or patity to control the number of solution.

If you are also interested in this kind of series, I really suggest checking out these series. stephane.bura's binary Sudoku(rules becoming more and more simple) hamslice's Shattered Palindrome(It just getting harder and harder)antichaos's Grand Tour Sudoku(why snake don't have this kind of idea)