The Classics are must-see, must-read, must-play works revered by The Verge staff. They offer glimpses of the future, glimpses of humanity, and a glimpse of our very souls. You should check them out.
The Left Hand of Darkness is a classic by almost any measure: it's award-winning, having grabbed the Hugo and Nebula Awards in 1970; and it is genre-defining — famed literary critic Harold Bloom said that it was this book, more so than even Tolkien, which had "raised" fantasy to the stature of "literature." Most of us out here in the real world, though, have long known that the distinction between literature and sci-fi / fantasy is a semantic one, and yes, Ursula K. LeGuin's books are fine proofs of that, though they're far enough off the beaten path of popularity that it's just possible you've never read one. That's all about to change.
The Left Hand of Darkness is one piece in a large series of LeGuin books known as The Hainish Cycle which all occur in the same imagined universe(s), though they stand alone exceptionally well. This particular novel tells the story of Genly Ai, an envoy for the Ekumen, a collective of many planets set in the far distant future of the Hainish world. Genly Ai travels to the planet Gethen in order to convince the civilization to join the Ekumen, an alliance to further trade and communication among the planets. Reading The Left Hand of Darkness, one is left with the sense that the writers of Star Trek: The Next Generation were inspired to pen some of its best moments by LeGuin's work.
What makes the novel so immersive is that unlike many "imaginary" worlds, LeGuin's feels fully realized and three-dimensional: reading it, you experience the full weight of a real history behind it, and sense the grind of time, evolution, and progress in the background of external plot points — and she manages to do it in under 300 pages! This book, along with The Dispossessed, makes up the two strongest pieces in a seemingly infinitely expandable universe of literatures. In that respect, The Hainish Cycle read truly like a "cycle," the way that the tales of Arthurian legend, or even say, Batman comics, do. One feels that the stories could simply keep appearing, because there are so many alleys and nooks left unpursued.
It's probably not possible to say much more without veering into the territory of spoilers, so, if you're looking for a way into reading the best of science fiction, fantasy, and literature (with a nice dose of feminism thrown in for good measure), The Left Hand of Darkness is a great place to begin. Oh, and if you really don't want to read the book, rumor has it that, after all these years, both a film and a video game based on it are in the works.