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.
Mammal is a small-to-medium-sized treasure-hunt game with mild puzzles. As the human slave of reptilians, you are tasked with eradicating all traces of mammals from a museum.
(Spoiler - click to show)This is a fairly grim premise, since you're effectively a Sonderkommando. The wider context of the purge is never explicitly stated, but there's ample evidence that it has been a violent and chaotic process. The featureless protagonist shows no signs of emotional reaction, and dutifully goes about a set of simple tasks that are perfectly familiar to an IF player: find and identify the treasures, solve some mild puzzles to secure them, return them to the trophy-case. The PC is wholly subsumed by their role.
There are some obvious homages: the skip as trophy case is a throwback to Ad Verbum, and the reptilians bear no small resemblance to Dr. Sliss of Rogue of the Multiverse. (If there are any direct references to the TMBG song, I wouldn't notice them.) More generic stock IF devices are common, too: a crowbar to pry things with, a wandering cat. This is about the morally numbing effect of familiarity, of how having an excellent practical grasp of how to do something can make it seem less ethically troubling. That this is a mechanically unremarkable game is kind of the point. The puzzles are just fiddly enough to engage your attention and keep it away from the elephant in the room. Ultimately, you incinerate yourself for the lousy last point. (I assume; there's a point or two that I haven't found.)
Mammal is not an ethically deep work; it has a single trick to pull, a single point to make. But it's cleverly handled, and it delivers a mean little moment of realisation. And it's very clearly not about the rather tired point that players will cheerfully do atrocious things if shepherded by gameplay; rather, it takes that as read and takes advantage of it.
(There is one small bug: if you incinerate yourself while holding other mammals, the other mammals are not incinerated.)