The Sims 2 filmmaking legal usage

I have noticed that a lot people have a hobby of creating films using the Sims 2 as a substitute to recruiting human actors and an actual crew. My question is, suppose somebody was to create a film using the Sims 2 and sell digital copies of it online, would that be illegal? My beliefs are yes because the Sims is a copyrighted game where unlike live action filmmaking or animation, you are not creating content from scratch, you are simply using an already existing game to create content for films.