The Warbler's Nest is an interactive fiction about perception: what seems to be going on may or may not be what is actually going on.
But many of the other games that explore the same territory do so in order to talk about the nature of mental illness, self-deception, or confusion about one's own identity: that is, they're presenting the crisis as one that occurs within the protagonist.
In The Warbler's Nest, the double vision is about what the protagonist knows vs. what the player knows. The game reports something in the protagonist's voice, but there are enough signals to the player to encourage him to at least consider the situation based on a 21st-century understanding of reality.
Having the player understand more than the protagonist has been used for humorous effect a few times: Grunk in Lost Pig reports experiences that the player is better able to interpret than the protagonist, and one of my favorite moments in Treasures of A Slaver's Kingdom involves intentionally letting the protagonist fall into a trap he's too dumb to notice.
But this time around, the dissonance isn't a joke, and the point isn't about people being slow-witted. Instead, it's about the importance of the world views we apply to everything we see, and how much tragedy may be in the mind of the onlooker.
The Warbler's Nest also uses the textual nature of the medium to full advantage. Every description, every atmospheric detail deepens the ambiguity of the protagonist's situation. The protagonist's own thoughts become a source of subtle menace. What's more, the words you choose to talk about the things in your environment affect how the game plays, because they express what you think is going on.
[If you've never played any interactive fiction before, you may like this condensed guide for help with command types.]