I saw it over the weekend and was a little mixed about this. I don't think it's a spoiler to say that his play dips into sci-fi, and that does add a level of intrigue in the first half of the show, but I found the more grounded parts of the show the most interesting: the siblings' relationships with each other and with their father and how they each approached familial obligations. I was sitting in the second row and there's a significant part of the show that takes place on the roof of the house, and while I don't think I missed anything important, it did feel a little uncomfortable being slightly obstructed, so if people are looking for seat recommendations, I'd recommend sitting around halfway back in the theater.
I'm really unsure what to make of the sci-fi parts of this, and would love to hear others' thoughts
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I felt like there was never a full payoff to all the hints leading up to the family room scene. So Joe and Mona are aliens (or at least Joe believes so) who have come to inhabit Earth, and while Mona had died on Earth, she still remains elsewhere (possibly referenced by her return as Crystal). I'm assuming that Joe's alcoholism/dementia are partially because of him trying to reconnect with Mona again, or maybe the result of living somewhere he's not native to? I was trying really hard to assign meaning to things, but there were just so many things that happened that I can't even remember them all (I think Mona mentioned she never wanted to be a mother and that's why she hung herself?)