8/10 from me - don't understand the hate.
I decided to give the movie a whirl after coming across the trailer on youtube. While I do understand that the second half films different from the first half of the film and it was venturing out on what felt like something out of the Outer Limits/Twilight Zone (picked that up from another thread but agree with the idea) it was still enough to keep me intrigued.
I didn't hate the ambiguous ending at all, I thought it was done well enough and it didn't end abruptly. Is it a simulation or is it not a simulation? At that point, it doesn't really matter at all simply because their 400 days is up. But since I don't mind making up my own ending (having given been the opportunity), I'm guessing that it's not a simulation and they only just had a prerecorded message played for them.
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Death is the standard breach for a complex prize.