It was made in a week by cdaniels7088. He was still in school. It was made for a competition in the school. I don't think they were allowed to use premade engines.
@@mtaimoorkhan863 some people use scratch as a stepping stone to programming games, especially when they have no experience in making games and/ or the knowledge behind how the order of code translates into what the running project shows. Of course you can code simple games with html, css, js and other languages, but this is a way for people to understand what is and isn't possible and understand the basic structure of how to start a project.