Technically, I don't think so. But it can actually be pretty easy to cross the barrier between enjoyably difficult and borderline impossible. Of course, there's always going to be someone who persists and manages to beat a stage you determined was not worth the effort, but that's different. Slapping on Bullet Hell, Head Hunter, and High Velocity will guarantee you a style of gameplay that doesn't gel with Pistol Whip's intricately crafted, rhythm-based mechanics, for example.