The Cursed Child and BTTF II
I enjoyed a lot reading the Cursed Child, but I found the general concept too similar to "Back to the Future II": time-travel results in a terrible alternate reality; getting stuck in the past without any time-traveling instrument; leaving a message to be read in the future, etc.
I am not suggesting Rowling committed a plagiarism. "Inspired" is a better term. Still, I'd prefer more original idea.
Did anyone feel the same?