Sudoku-like number puzzles have been appearing since the 1800’s as far as we know, but the modern form of the puzzle starting gaining popularity in the 1980’s when they became known as ‘Sudoku’ and published by the Japanese puzzle company Nikoli. Today the classic Sudoku puzzles are widespread and new variants and rules are appearing all the time.
Review rules and history of Sudoku on Wikipedia.
Algebraic Thermonuclear Sudoku - Puzzle 01
Rules:
Normal Sudoku rules apply.
Along the thermometer shape, digits must increase from the bulb end.
The grey cells form a magic square (every row/column/main diagonal in the grey square must sum to the same number). The magic square sum is "x".
The dotted lines form cages, the sum of all the digits in each cage must equal the value shown in the corner of the cage. Digits in a cage do not need to be unique.