I believe the proper term is 'old skool'

The Cat Piano, a winner of multiple Australian film awards, created by The People's Republic of Animation

This traditional-appearing 'flat animation' piece is set to a narrative poem by Eddie White, read by Nick Cage, and depicts an adventure of the narrator, an anthropomorphic cat living in a musically-inclined feline city. (In other words, it's almost as good to listen to as to see.)