In 1989, it earned the distinction of being the first game ever published as a CD-ROM. In the 1990s, the original Apple Macintosh HyperCard version started receiving ports to other platforms, including MS-DOS, Windows, and most recently, the iPhone.
The Manhole was followed by a Spiritual Successor IN SPACE, Cosmic Osmo.
This game provides examples of:
- Can't Take Criticism: Hamlet Pig will get irritated and refuse to let you pass if you say you don't like his (non-sequitur, randomly generated) poem. The rhinoceros lady he's guarding (presumably his superior) will tell you to just humour him whenever you speak to him because "his brain is very small".
- Chess Motifs: The flamingo's domain.
- Edutainment Game: Very mild educational elements, such as a book of the alphabet and a few lines of dialogue written in both French and English.
- Elevator Gag: The "New and Enhanced" edition added some on the floors between the sunken ship and the walrus's island.
- Featureless Protagonist: The player character is implied to be a kid, and that's pretty much the only thing you know about them.
- Macro Zone: And Macro Zones within Macro Zones. You can sail a tiny boat around the teacup of a rabbit who lives inside a fire hydrant.
- Mythology Gag: In the Masterpiece Edition, the rhinoceros at the top of the tower tells you she was a flamingo in a previous life, since you met a flamingo there in the original version of the game.
- Non Sequitur Environment: By climbing a beanstalk, you can find a forest above the clouds or a tropical island under the eponymous manhole; a tower sitting in the middle of the forest turns out to be a rook in a giant chess set bobbing in an underground canal, but only when you reach the top; a perfectly ordinary elevator can open in a sunken ship; a wrong turn in one of the canals can take you through the teacup of a rabbit living in a fire hydrant across from the manhole...
- No Plot? No Problem!: The game has no plot or storyline to speak of, just wandering around a bizarre world to see what there is to see.
- Our Dragons Are Different: This dragon is a laid-back dude in Cool Shades.
- Portal Picture: There's a picture of a dragon that will take the player to Mr. Dragon's lair...uh, crib. Also in the ship is a picture of a boat, where, after making it sink, you can teleport to the base of the beanstalk.
- Product Placement: Mr. Rabbit keeps a collection of books the player's encouraged to read, including Alice's Adventures in Wonderland, The Wind in the Willows, The Lion, the Witch, and the Wardrobe, and Winnie the Pooh.
- Shout-Out: The whooshes of a passing spaceship form the five-note motif from Close Encounters of the Third Kind.
- In the CD-ROM version, clicking on the TV in the house plays you a trailer for Myst.
- Take That!: On a shelf of children's books with pop-up descriptions of what they're about is a textbook called "Metaphors of Intercultural Philosophy"."This book isn't about anything."
- Updated Re-release: The "New and Enhanced" edition, the "Masterpiece" edition...
- Warp Whistle: Mr. Dragon's TV set. You warp to a different place through it depending on what channel you pick, even back to the title screen.
- Welcome to Corneria: Most of the characters have only a couple of lines of dialogue (some only have one) and they'll just repeat themselves if you try to talk to them further.
- Wide-Open Sandbox: One designed for kids, in that there's no enemies to fight or treasure to hoard. Just looking around poking in every nook and cranny to see if anything fun happens.
- World of Chaos: There's no rhyme or reason between how the game's areas connect at all. But then, that's part of the fun.
