Repeated Killer N1 2017

Last day of the year. Had created this puzzle as an example for the IB of the upcoming UKPA Sudoku Championships 2018.

On a lighter note, I thought of naming it as Serial Killer rather than repeated killer :)

Rules of classic Sudoku apply. Additionally, digits on the top left of a cage denote the sum of the digits inside the cage. Digits CAN repeat inside a cage.