How can you win if you are the murderer/ess? Because the premise is figuring out the murderer's identity by way of evidence. If you can find the evidence of your guilt before anyone else does, that means you can destroy it and get away with it.
That doesn't explain why the game requires you to repeatedly destroy any possibility of pinning the crime on someone else.
If you don't seem to actively look for the murderer the others will be suspicious.
In the 3rd ending I assumed that being the undercover agent, the Mr. Green who appears in the film is NOT the Mr. Green who received the invitation; Wadsworth working off of an informant's tip had never seen the Real Green, and the FBI sent a fake in his place, thus while real Green was gay, Fake Green had a wife to go home and make love to
It helps that the plan to have a picture of him holding hands with a man to be shown as the evidence was being burned was changed.
"Shake, Rattle, and Roll" features prominently in the soundtrack. "Shake, rattle, and roll..." as in dice.
After the bloodbath, we discover that all the visitors were either blackmail victims or Boddy's accomplices. The deaths of the latter supposedly clears the killer of the chance of prosecution, as the only witnesses are still subject to blackmail. Except we never hear how Mr. Boddy found out about Mr. Green.
Makes sense in light of the third ending. In that one, Green is an undercover FBI plant, investigating Mr. Boddy. Since the best way to prove that he's blackmailing people would be to get blackmailed himself, Green could simply make up a likely story and intentionally get someone to leak it. The other endings are more unclear. Maybe Miss Scarlet's brothel doesn't just employ female escorts?
That's an interesting point, and possibly supported by him saying he knew Miss Scarlet; he claimed it was just because he worked in Washington too, but maybe there was more to it...
Mr. Green gave a strong hint he's not supposed to be there. Remember, Mr. Green exposed himselfnote Please. We have ladies present!, with a confused looking Wadsworth briefly checking the evidence. He didn't know Mr. Green's blackmail!
And yet Wadsworth recognized him at the front door in the beginning. Oh, you must be Mr. Green. Clearly he was expecting someone fitting Mr. Green's description to attend the party, although we'll never know what the evidence packet said about him.
Not necessarily—"You must be Mr. Green," isn't what you say when you recognize someone—it's what you say when you meet someone you haven't met, but are expecting to meet. I.e., he knew what all the others looked like, but on seeing the lone unfamiliar face, he concluded he was the one he hadn't met yet.
Am I the ONLY person who thinks he doesn't look confused and looks more like he's thinking something along the lines of disgust and relief that he doesn't have to reveal that, which was in the time period, probably the most revolting of the secrets, since he won't elaborate on the crimes of the others? He'll gladly list what Peacock, Plum, and White did but can't bring himself to continue, and the camera shoes Mr Green at that moment, implying he was going to talk about him, next.
I always thought the evangelist was supposed to be Green's informant; in none of the endings does Wadsworth look surprised to see him, implying he'd been invited (though whether he was told to come in that disguise or did it on his own is unknown), and whether the man was Wadsworth's boss or Green's he could have access to Green's secret, or claim he does, or be able to learn it.
Alternatively, maybe Green was actually gay all along and the last line was his way of saying "My secret is safe, suckers!"
this makes sense, considering even the tiny actions he does. When he and Yvette are walking back upstairs after locking the Cop in the library, she tries to either take his hand or his arm, I forget which right now, and immediately he pulls away from her in a way that doesn't seem to have to do with his being married. It wasn't quick, it was like a subconscious gesture.