Dial Code Santa Claus aka Deadly Games (1989)

Thomas is a typical 1980s kid: he loves Rambo, computers, role-playing games and his dog. While mom's away at the office on Xmas Eve, Thomas and his grandfather are left home alone -- perfect timing for a disgruntled, perverted, bloodthirsty Santa Claus to raid the home down the chimney. But Hell hath no fury like a mulleted ten-year-old with an arsenal of toys!