The opening half was excellent, brilliantly contrived idea, with a good plot to go with it.
As with so many films, it went rapidly downhill and for the same reason as so many before it.
I have absolutely no idea why one of the characters had to start killing the others and turn it into any low grade slasher film.
The first death fair enough, that went with the story but a complete transformation of one of not more of the other characters added nothing.
It also was not always easy to know which reality the plot was in at the time.
As with so many films, it went rapidly downhill and for the same reason as so many before it.
I have absolutely no idea why one of the characters had to start killing the others and turn it into any low grade slasher film.
The first death fair enough, that went with the story but a complete transformation of one of not more of the other characters added nothing.
It also was not always easy to know which reality the plot was in at the time.