Group Sum Sudoku (Daily Sudoku League #44)

It's time for a puzzle that carries the weight of championship history in our Daily Sudoku League! This Group Sum Sudoku is a fantastic brain teaser that uses circled sums to guide your logic. As you solve, remember that each circle's number is the total of the cells it overlaps.

After returning from the World Puzzle Championship 2005 held in Eger, Hungary, the Indian puzzle team was greatly impressed by the creativity and puzzle-design skills of the Hungarian puzzle creators. Their innovative puzzle ideas inspired many of us to learn the art of creating new puzzle variations.

A group of Indian puzzle enthusiasts then formed a Yahoo Group where members created and shared one new puzzle every week. Other members would solve the puzzle and provide feedback, helping everyone improve their puzzle-construction skills. I created this Group Sum Sudoku puzzle in March 2007 as part of that learning process.

This unique Sudoku variant was selected for the Indian National Sudoku Championship 2007. Later, it was also featured in the World Sudoku Championship 2008 held in Goa, India. In every championship where it appeared, this Sudoku puzzle earned a reputation for being one of the most challenging and feared puzzle types among the participants. The puzzle made another appearance in the finals of the Times Sudoku Championship 2014 in Mumbai.

The feedback I received for this puzzle was very encouraging. Therefore, I am pleased to publish this Group Sum Sudoku as my 44th contribution to the Daily Sudoku League.