“Amp House Massacre” (*1/2 out of four) was strictly formula stuff about a group of social-media influencers and friends (Kara Royster, Pedro Correa, Ciera Angelia, and others) who party at a mansion in Hollywood Hills where they are stalked by a killer who reveals their deepest-and-darkest secrets before killing them off. The kind of movie that was a lot more fun in the ’80’s but is hollow and by-the-numbers now. Film’s ending is a real letdown, if you make it that far.