Deadly Games
36.15 code Père Noël (original)
Thomas, a very intelligent and resourceful child, is left alone with his beloved and fragile granddad on Christmas Eve, when a psychopath dressed as Santa Claus breaks into their mansion and starts chasing them. Thomas will do whatever he can to save himself and his granddad, leaving much of his childhood innocence behind.
Starring Brigitte Fossey, François-Eric Gendron, Louis Ducreux, Alain Lalanne, Patrick Floersheim, Stéphane Legros
Watch "Deadly Games" on shudder-shudder-subscription released in 1990. It's a action & adventure and horror movie, and has a rating of 6.4 out of 10 from Imdb which is usually fine for this kind of movie.