Lots of people get excited about Albert Camus. I agree that he's a good writer, but after reading a dozen or so Sartre plays, his themes don't seem very original. My feeling has a great deal to do with my not being in "the middle" of the existentialist movement. Since Sartre introduced me to their themes and ideas, he appears to me to be their champion.
Caligula for instance, is almost exactly the same book as Sartre's Le Diable et le Bon Dieu: a powerful military leader decides that he is going to create" -- and since all the good things that can be done have already been done, he's going to be evil and nasty.
Le Malentendu is fun, though, for its sick, twisted premise: a son returns home after not seeing his mother and sister for years. He stays at their hotel without telling them (as a surprise). Unfortunately, mom and sister have been poisoning and robbing all the hotel guests, and they don't make an exception here. Yow!