Killer sudoku - Wikipedia

File:Killersudoku color solution.svg - Wikipedia

KillSud - killer sudoku - Apps on Google Play

Sudoku

File:Sdk ex08e.gif - Wikimedia Commons

Constraint Solver Part 6: Backtrack and Sum constraint

Activity Workshop - Sudoku

KillSud - killer sudoku - Apps on Google Play

Sudoku and Graph Coloring — NetworkX Notebooks

According to wikipedia, this is currently the least known clues killer sudoku (no killer sums, just eight < > = signs). I solved it and it's amazing : r/sudoku