This is not a game. But you should play it, because it is a personal essay on identity and in this regard it is well-written and interesting.
Don't play it if you are looking primarily for a game or a story, though I recommend you check it out as some point in any case.
Fogged Up Mirror is interactive fiction more or less the way you have to interact with a browser to visit a web site. There is a recurring image of words being wiped off a mirror, which strikes me as a rather interesting means of tackling something like identity labels; unless actively wiped off, a word written on a mirror will fade but show up again when the mirror is fogged up. Labels persist unless we take conscious action against them.
Nevertheless, this image is used sparsely and Twine is employed here less as a cinematic technique than as a sort of filing system. The reader picks different categories of identity and hears the author's introspection on her self-perception through these categories. Holland delivers her thoughts in honest, straightforward language that makes them accessible. I don't necessarily mean "accessible" in the sense of "will convince bigoted people of the validity of her position"; what I mean is that his thoughts remind me of what I've thought about my own identity. Her words are spoken the way I speak them in my head. The thoughts are not at heart judgmental, though they can express frustration with people. There isn't any attempted ethical justification for choosing these labels or inhabiting these identities; the underlying, intuitive assumption is that the author deserves respect by virtue of being a human being, which is probably the best universal reason to be OK with exploring identity in this way.
"Labels don't matter much, until they really do." That's the opening sentence. In the way that words on a mirror appear when you breathe on them, identities often don't occur to people until they're challenged. I never gave much thought to my sexuality until my social circles became largely composed of non-straight people. I had little sense of my gender until I started to live in a national culture which prized masculinity above most human qualities. As a result I felt a kinship with the author, even though in many ways his personal experiences are different to mine.
I rate Fogged Up Mirror four stars because, low interactivity aside, Twine's use is appropriate here: none of the identities you can choose to explore are given priority of placement over the other, encouraging you to read them and discard them in any order. And the content is not unique in any surface sense, but it engages the reader and is worth your time. Read it not for art or gameplay or story, but for a simple, elemental glimpse into someone else's head.