Entropy Spirals: Even the Solve for this Sudoku is a Spiral!

Today's Puzzle:

Another great puzzle from Will Power with a lovely solve path and pattern too.

Link to Play Along:

Entropy Spirals by Will Power http://tinyurl.com/SudokuSleuthEntropySpiral

Rules:

Normal Sudoku rules apply.

Any set of three neighbors on blue lines contain one low number (1-3), one middle number (4-6) and one high number (7-9).

KILLER CAGES- Numbers in cages sum to the number in the top left corner of the cage.

KROPKI PAIRS- Numbers with a black dot between them are in a ratio of 2:1. Not all possible dots are given.