Within the first couple of minutes if “The Invitation” you understand what director Kusama is doing. She is setting up Will as the skeptic or even the paranoid guy who cannot just enjoy the party he and his old buddies have been invited to, but smells a rat around every gesture. We assume that we have to play along and assume that the director and author want us to assume that we think he is wrong about all this, because it would be so obvious, which again would lead us to believe that he is right about all this, which again might be reason enough to doubt it … so you have to decide which side you are on: is Will just a party pooper, or is there something going on that puts all the guests in danger? The experienced cinema audience will realise that whenever John Caroll Lynch gets invited to the party, there is a maniac or at least a child molester around, no? Will David play some music in the end (loved Treme!), or will he kill everybody and serve them to his guru for dinner? So you got your clues, and need to put the pieces together before the reveal comes, for maximum satisfaction.
You can only play this game for a while, then it gets boring. “The Invitation” does ok in deciding when to stop playing and start getting serious. But then again, once you stop playing, you change genre, and you either end up in Bunuelian social drama (guests discussing their relationship issues over dessert) or a slasher film. Both options are not very appealing unless very well done. If you only start doing them halfway through a film, what are the chances of getting it right?
So this is a bit of several genres, with nice ideas and very good actors, but then again, the film never reaches perfection in either genre. As soon as the truth about the setup has been revealed, the whole thing deflates quite a bit, and not even the strong hands of John Caroll Lynch can rescue it completely.