While the original Friday the 13th was a barely-released low budget flick with a definitively conclusive ending, that can't stop the hollywood sequel machine from kicking into high gear in record time! Introducing Jason as the killer, this particular entry in the series isn't actually seen as a horror movies high point despite paving the way for the iconic villain. (blog post) Mainly action movies because they way they did it was incredibly stupid, even for horror movie standards.
Source: Friday the 13th Part 2 Movie Review - Decker Shado