If you're not careful and you noclip out of reality in the wrong areas, you'll end up in the Backrooms, where it's nothing but the stink of old moist carpet, the madness of mono-yellow, the endless background noise of fluorescent lights at maximum hum-buzz, and approximately six hundred million square miles of randomly segmented empty rooms to be trapped in. God save you if you hear something wandering around nearby, because it sure as hell has heard you.

So stated an anonymous 2019 thread on 4chan's /x/ imageboard -- a potent encapsulation of liminal-space horror that gave rise to a complex mythos, exploratory video games, and an acclaimed web series (previously; soon to become a major motion picture from A24!). In the five years since, the evolving "Backrooms" fandom has canonized a number of other dreamlike settings, from CGI creations like The Poolrooms and a darkened suburb with wrong stars to real places like the interior atrium of Heathrow's Terminal 4 Holliday Inn and a shuttered Borders bookstore. But the image that inspired the founding text -- an anonymous photo of a vaguely unnerving yellow room -- remained a mystery... until now.

...turns out it's from a 2003 blog post about renovating for an RC car race track in Oshkosh! Not quite as fun a reveal as for certain other longstanding internet mysteries, but still satisfying, especially since it includes another equally-unsettling photo (and serendipitously refers to a "back room"). Also, due credit to Black August, the SomethingAwful goon who quietly claims to have written the original Backrooms text. Liminal spaces previously on MeFi:

Discussing the Kane Pixels production (plus an inspired-by series, A-Sync Research). Note that as the Backrooms movie takes shape, Kane is continuing work on an intriguing spiritual successor: The Oldest View The Eerie Comfort of Liminal Spaces A Twitter thread on being lost in a real-life Backrooms space Inside the world's largest underground shopping complex A 2010 post about Hondo, an enigmatic Half-Life map designer who incorporated "enormous hidden areas that in some cases dwarfed the actual level" MyHouse.WAD, a sprawling, reality-warping Doom mod that went viral last year AskMe: Seeking fiction books with labyrinths and other interminable buildings

My personal favorite liminal space: the unnervingly cheerful indoor playground KidsFun from '90s-era Tampa -- if only because I've actually been there as a kid (and talked about its eeriness on the blue before). Do you have any liminal spaces that have left an impression on you?

Life is not a continuous line from the cradle to the grave. Rather, it is many short lines, each ending in a choice, and branching right and left to other choices, like a bunch of seaweed or a genealogical table. No sooner is one problem solved than you face another growing out of the first. You are to decide the course of action of first Helen, then Jed, then Saunders, at each crisis in their lives. Give your first thought, without pausing to ponder.

Consider the Consequences!, a 1930 gamebook co-written by author Doris Webster and crusading journalist Mary Alden Hopkins, is the earliest known example of a choose-your-own-adventure (CYOA) text, offering players a series of forking narratives for three interconnected characters with 43 distinct endings, fifty years before the format was popularized (and trademarked). Just a few years ago this pioneering work was at risk of falling into near-total obscurity. But thanks to the efforts of jjsonick on IntFiction.org, you can now read the book on the Internet Archive (complete with nifty graphs of all possible storylines), or -- courtesy of itch.io developer geetheriot -- play the game online in an interactive fiction format powered by the Twine engine. More in the mood for radio drama? Listen to Audio Adventure Radio Hour's 2018 dramatic reading of the book (based on listener suggestions), and wrap it up with a delightful retro-review by librarian pals Peter and Abby on the Choose Your Own Book Club podcast.

Scans of the original book's dust jacket Demian's Gamebook Web Page has a detailed breakdown of the book's structure, including a user review that explains why this 94-year-old narrative remains fresh and relevant:

Even though people may find the idea of reading a book from the thirties off-putting, I found this to be a fascinating read. This being a book for adults, the choices included have really serious consequences, and the ability to play as either a female or one of two male characters allows the reader to gain greater insights into certain aspects of the social life of the era (such as social class, marriage, divorce, single motherhood, and women's increasing emancipation and participation in the labor force). The thirties were a time of significant changes in social norms, which are highlighted in a manner that manages to be both entertaining and educational. The book makes great reading material for people interested in subjects such as sociology or gender studies, especially because it makes the reader face the consequences of his or her decisions without ever becoming censorious or preachy. Contrary to what you might expect from a book from this era, the story deals with topics such as alcoholism, unmarried cohabitation, unusual family arrangements, political corruption, and even suicide without trying to obscure or sugarcoat their implications. It also details both player and nonplayer characters with a level of psychological depth I've very seldom seen in interactive fiction - the reader will find him or herself clashing with the social mores of the era, and how he or she responds to them will in turn shape his or her character's happiness in later life. Along some paths, the reader will find him or herself to be contributing to social change as his or her decisions successfully defy prevailing norms and taboos. Notably for such an early work, the structure of the adventures is quite complex, with several story branches crossing with each other instead of all the paths remaining separate. Overall, I highly recommend this book for its entertainment value and developed gameplay, as well as for having demonstrated the capabilities of the interactive medium in a remarkably early era.

Authors Doris Webster and Mary Alden Hopkins co-wrote a number of other innovative works, including algorithmic dating advice tome Help Yourself, personality assessment I've Got Your Number!, Self-Portraits ("A Novel Method of Taking Personality Photographs"), and Mrs. Grundy is Dead, a provocatively-titled etiquette book based on anonymous surveys from teens around the country on such questions as "What do you do when no one cuts in on your partner?", "How soon do you call a girl by her first name?", and "Do you take off your glove to shake hands?" More on the early years of interactive fiction: A Very Brief History of Gamebooks (up to 1979), by IF blogger Jason Dyer The Memory Machine podcast interviews Dyer on the history of text adventures [audio link]