My Bloody Valentine [George Mihalka, 1981]:
The valentine’s Day theme may have been better suited to a high school setting, closer to a film like Prom Night (1980) or April Fool's Day (1986) for example, so placing this in the confines of a blue-collar mining community with a backstory about a cursed town steeped in tragedy is certainly a choice. The identity of the killer seems like an afterthought here (I'm not convinced the twist stands up to much scrutiny, though a re-watch might be in order) but as an early example of the slasher genre this does a lot of things well. The use of the mine provides great production value and authenticity, and there are some really terrifying murder sequences, which take full advantage of the killer's incongruous and imposing look.
