A tiny, unusual little wordplay game, scarcely IF. World-model is irrelevant, and the parser only accepts one type of command. You are given words, and have to supply a rhyme for each word. Your score is how many acceptable rhymes you supply within 60 seconds. The framing is that this is a psychotherapy exercise; you're being asked whether you feel emotional state X, and you respond with, 'no, I'm feeling Y'. Y does not always have to be an emotion, since the game recognises a wide range of rhyming words, some of which aren't even adjectives.
On the one hand, gameplay is simple and easy, so much so that it's tempting to think of this as a toy rather than a game; getting a good score might take a few tries, but mechanically it's not difficult. The game tells you the puzzle's parameters straight off. On the other, the framing creates a weird uneasiness about the exercise. A fair amount has been written about how the psychotherapy premise of Eliza tended to make players take it more seriously. Similarly, WDHYF has something of the tension of a word-association game about it; it's a silly exercise, but there's the sense that you're being judged on it. This is particularly true because the act in question is laying claim to emotions, which is something people generally invest a lot in. Laying claim to an emotion can be a vulnerable act of self-expression, and it's also a commitment of sorts, a reinforcement; we don't look kindly on people who fake emotions, and we don't want to be seen as someone whose emotions change rapidly for no reason ('emotionally unstable' is a euphemism for 'crazy'). Saying 'I am happy' or 'I am sad' costs you something.
But because of the constraints you're usually forced to lay claim to a rapid, little-considered series of random, mismatched, nonsensical emotions. So there's a sense -- slight, but disquieting -- of brainwashing-exercise about this: repetition, illogic, pressure, self-obliteration.
What you get out of Encyclopedia Fuckme is largely going to depend on your reaction to its particular kinks: chacun a son gout. Normally, the polite thing to do here would be to list the particular kinks involved, but this would probably be spoilerish; it's a fundamentally transgressive piece, and the tension of not knowing what shit it's going to pull next is a great deal of the point. Still: this is not one of those Anthropy games in which lesbian BDSM smut is merely a mild aesthetic theme. You have been warned. (As someone who is not all that into most of its kinks, I ultimately found it more charming than offensive or gross, but it is possible that the Internet has jaded me.)
Its purpose is clearly pornographic, in that it appears designed to get someone off. It doesn't take itself very seriously, and it aims to squick you out by running roughshod over your boundaries, but (contrast Stiffy Makane: The Undiscovered Country) these seem in service to its pornographic aims, not a negation of them. It's largely about how being forced outside comfort zones gets people hot. The writing is headlong, hard-breathing and frantic, throughout: a great many of the choices are unpunctuated speech in all-caps, and the protagonist's conflicting motives of horniness and self-preservation are... not exactly understated.
As CYOA goes, it is very linear; up until the end, basically all your options remerge into the same central track. Many of the choices conspicuously make no difference. There's more than one ending, but the mechanics that distinguish them are not conspicuous from play. Its game-like aspects, then, are all about the surface, about employing the promise of interactivity as a tool to foster engagement. There's obviously some content-form relation here, although this is getting to be a rather old saw: yeah, the game is controlling, we get it.