[warning for spoilers, obviously]
Things in this game that would've been 10x cooler and more chilling if the Visitors weren't actually a real thing:
The first time you hear about Visitors is from your neighbour, who quotes his cousin you've never met, and he has a lot of "I don't know"s in his story
Despite his warnings, this neighbour encourages you to trust people and let them into your house, to never let anyone know you're alone. He later dies by trusting someone and letting them into his house, and they kill him
The government is the first to dictate the criteria of "Visitors", and claim things are caused by the "anxiety" of these Visitors. The government also describes the "signs" one by one, all of which are completely normal and common things for human beings to have or exhibit. This information is spread via the, seemingly only, news station. This news station is sponsored by the government. This news station is sponsored by the tools you need to use to test for Visitors. It's important to listen to the news.
The government encourages you to actively profile Everyone you see, and to report to the government immediately if you personally find anyone suspicious.
People come to your house asking for shelter and security. These people include children, and kind or weary travellers - but it also includes assholes and weirdos. The latter present far more "suspicious" signs, despite everyone in the game appearing off somehow (and drawn in the purposefully uncanny-valley style). So it's easy to turn the assholes and weirdos away, right? If they were humans, they'd be nicer, or more normal. They're probably Visitors.
People extend their trust to exist in your home. You can choose to shoot and kill any of these people, at any time. You face no repercussion for this - the government understands, of course; they could've been Visitors.
The local school could've been overrun by Visitors. Of course the Visitors would know to disguise themselves as human children, then we'd be less likely to suspect them. The school needs to be burned down, and all the children eradicated. We wouldn't want to raise a generation of Visitors, of course.
Humans are killing each other in the streets. But it's okay, because there could be Visitors.
The government agency in charge of managing the situation (and would you know, it's FEMA) can take anyone from your home, at any time, without permission. They just need to make sure no one is a Visitor. You never again see the people they took away - they must have been Visitors.
Some people come to you and they don't have perfect grammar, or they use the wrong words, or they stutter. Normal humans wouldn't do that, you should be suspicious of this. What if they're a Visitor?
Did you know that you could be a Visitor without realising it? If you're afraid you've become a Visitor, you can just call the government. Tell the government everything about yourself. Tell the government everything they should suspect of you. They're here to fix things. Follow the government agent, they'll help you.
Don't let anyone in. Don't talk to anyone. Stay inside your homes. The government is handling this. Anyone could be a Visitor. You can only trust the government. The government will protect you.
The world is ending. You don't want to die surrounded by Visitors, do you? You should just kill everyone in your house, to be safe. You shouldn't have let anyone in anyway, what were you thinking? Just get rid of everyone, so there's no chance of trusting the wrong person. If they aren't Visitors, then why would they act so suspicious? You let them into your home, you trusted them, and they have the audacity to behave in concerning ways, with their human-looking eyes and teeth and hands and bodies. They are Visitors taking advantage of your humanity. You should show these Visitors who they're messing with. You should just kill them all.
