Previous games by Infocom used a parser evolved from the one in Zork I, but for Zork Zero, they designed a new LALR parser from scratch. Zork Zero's parser has some innovative features. If it notices if a player is having trouble with it, it offers helpful suggestions, such as sample commands.
Three of the four graphical mini-games are based on older logic puzzles. Peggleboz is a version of peg solitaire, Snarfem is Nim, and the Tower of Bozbar is Towers of Hanoi. Other puzzles based on established logic puzzle types include a river-crossing puzzle with a fox, a rooster, and a worm, and a Knights and Knaves puzzle in which violently xenophobic Veritassi and Prevaricons are truth-tellers and liars respectively, and peaceful Wishyfoo are alternators.
Lord Dimwit Flathead the Excessive certainly earned his nickname. Never one to do things on a small scale, when Dimwit decided in 789 GUE to have a statue erected in his honor, it had to be the largest statue ever. This angered a local resident of Fublio Valley (where the statue was built), Megaboz the Magnificent, who cast a deadly curse over Dimwit, the royal family, and the entire Empire before disappearing. The king's conjurers employed their most powerful magic in an effort to counteract the curse, but they were unable to save Dimwit and his eleven siblings; they only managed to delay the kingdom's destruction temporarily.
The game begins with a brief prelude in which the player is a humble servant in Lord Dimwit's scullery. Present when Megaboz appears and casts his fateful curse, the player manages to grab a small piece of parchment left behind in the chaos.
94 years later, the strength of the counter-curse is rapidly fading. If the curse can't be lifted by Curse Day, the anniversary of Dimwit's death, the Empire will surely fall. The reigning monarch, Wurb Flathead, has sent out a call in desperation: anyone who can save the Empire will be given half its riches! Predictably, this results in an avalanche of crackpot treasure seekers, none of whom have any more luck than did the royal sorcerers.
As the game begins in earnest, it is Mumberbur 14: Curse Day. The erstwhile curse-breakers have fled, along with everyone else in Flathead Castle. The player, a descendant of the servant from the prelude, awakes on the floor of the castle armed only with the scrap of parchment. The only other person around is the court's jester, who alternately helps and opposes the player in the quest to lift the curse.
Two items belonging to each of the "accursed twelve" (that is, Dimwit Flathead and his eleven siblings) must be placed into the cauldron and the magic word must be spoken. The game revolves around gathering these twenty-four objects and discovering the magic word. To accomplish this, the player will play the legendary game of Double Fanucci, travel to every corner of the Empire, solve a collection of riddles and logic puzzles, and visit the enormous statue that started all this trouble. There are even visits to locations such as the top of the world, and under the world (from which the player can fall). Flamingos, magic, bottomless pits and a unique sense of humor all feature along the way.
What happens when the curse is finally lifted is the game's final surprise. If you leave the castle and pass the perimeter wall, you arrive at the opening scene of Zork 1.
This videogame contains examples of:
- Anti-Villain: The Jester, aka Megaboz, seeks to wipe away the legacy of the astoundingly Stupid Evil Flathead Dynasty so Quendor can be free of their long shadow. Unfortunately, he pursues this noble goal primarily by playing stupid practical jokes on you and forcing you to beat him at Stock Puzzles.
- Artistic License – Economics: Quendor has only one bank, all trade is between different branches of FrobozzCo, and 90+% of everybody's income is taken in taxes to pay for government projects that mainly serve to boost King Dimwit's ego. This might explain why Dimwit's reign contained three civil wars and an average of 3-4 tax riots a day.
- Big Creepy-Crawlies: The Jester summons a giant bed bug to block your path at one point, what do you do? Fall asleep. It immediately goes away.
- Black Widow: Lucrezia Flathead's backstory, no question. Eighteen husbands, and only the first three survived past the wedding night.
- Bottomless Pit: Veteran Zork players may find it odd that darkened areas threatened death-by-bottomless pit instead of the traditional grues. Apparently, grues originate from these pits, because when the player uses a special "anti-pit bomb" to fill the pits and end the danger, they escape destruction by fleeing into the GUE. They threaten the life of the player in darkened areas for the rest of the game.
- Calvinball: Double Fanucci. The trick is to find out the one rule that will result in your victory and execute it, but any number of other, unknowable rules can block your victory plays. Fortunately, you can just try again.
- Copy Protection: Extensively. Many puzzles cannot be solved at all without knowledge contained in the game's bonus materials. For example, the giant toad in the River Delta will not respond to you unless addressed by his formal name, which is not recorded anywhere except on the Flathead Calendar. Since the only permanent light source in the game is hidden behind one of these puzzles, the player cannot progress much beyond the main castle area without reading the bonus materials.
- Developer's Foresight:
- There is a device that can transform you into whatever is placed in the other of two chambers. If you type the command "DIAGNOSE" most of the time, the parser will respond "You feel fit as a fiddle." If you transform yourself into the violin, it will instead say "You feel fit as a fiddle. In fact, you ARE a fiddle!"
- While attempting the Knights and Knaves puzzle, saving is disabled to prevent you from solving the puzzle through Save Scumming or brute force.
- Disproportionate Retribution: When King Dimwit Flathead had a huge statue of himself erected in Fublio Valley, it blocked all sunlight from reaching the home of the titular wizard Megaboz. Megaboz's reaction to this injury was to place a death curse on Dimwit, his family, and his entire kingdom! Dimwit and his eleven siblings died immediately, and the Great Underground Empire fell ninety-four years later. Dimwit likely had thousands, if not millions, of people with legitimate grievances who wanted to kill him, but Megaboz's relatively petty revenge was what ultimately did him in. Megaboz ultimately helps you "thwart" his own curse however, and suggests that his reasons weren't as petty as he had led people to believe.
- The Dog Was the Mastermind: The end of the game reveals that the Jester is Megaboz.
- Gender Bender: (see Human Chess below) in the Giant Chessboard area, if you send a pawn (They're all male) to the end of the board, he transforms into a Queen.
- Great Big Book of Everything: The Encyclopedia Frobozzica, found in the East Wing of the castle, contains knowledge on every topic under the sun, except for the rules to Double Fanucci, which would themselves require a book even larger than the Encyclopedia itself.
- Highly Specific Counterplay: There is a highly detailed and intriguing puzzle where you play the legendarily complex card game Double Fanucci against the Jester. Sadly, no amount of skillful play with solve the puzzle unless you use a Highly Specific Counterplay in response to a certain action, which is listed in the documentation. It's just Copy Protection.
- Human Chess: If you don Dimwit's cloak, you get transported to a lifesize chessboard. Aside from ordering the human pieces around, you can't really do anything there, but it does help you in a later puzzle.
- Knights and Knaves: A classic variant occurs here. However, which is the Knight and which is the Knave is randomized every time you attempt the puzzle, and you can't save while attempting it.
- Logic Bomb: In Port Foozle, an Inquisition is executing everyone they can find, including you. You are allowed a final request; if they can grant the request, they do so and then hang you. If they cannot, you are beheaded. Escaping involves dropping this trope on the none-too-bright executioner (the solution: 'Executioner, behead me'.
- Loony Laws: In the Feelies it is revealed that King Dimwit Flathead made every Thursday into "Birthday," on which everyone had to give him presents.
- Mad God: Aside from the god part, the Jester fits the criteria. He loves using his seemingly omnipotent magic to troll and screw with you, and uses it to do completely random/chaotic nonsensical things, and breaks the fourth wall a few times.
- Meaningful Name: A character named Lord Dimwit Flathead the Excessive doesn't sound very bright.
- Mini-Game: There are four of them.
- Needle in a Stack of Needles: FrobozzCo Headquarters is 400 stories with 4 offices per floor, with only a hint in the Feelies as to which room, if any, is significant. Fortunately, the only noteworthy room is on a relatively low floor.
- Nintendo Hard: Even by Interactive Fiction standards this game is an absolute bastard. Fortunately, its hint guide was built into it.
- No Celebrities Were Harmed: Almost all the Flathead Siblings are based on famous historical figures. Checking your inventory while wearing the glove earns a comment from the game saying you resemble "Famous singer Michael Flathead, formerly of the Flathead Five". Also found is a pin-up of Ursula Flatead, likely a reference to actress and model Ursula Andress.
- Prequel: As the name suggests, this game actually occurs before Zork 1.
- Recursive Reality: The world sits on the back of a giant brogmoid (a sort of goblin or troll who are, ordinarily, short humanoids), but you can discover the feet of a second brogmoid at the top of the world. Sentient fungi live in their ears and toes. Dropping off of the bottom of the world reveals another world below (before the player dies on impact, of course), presumably resting on the back of yet another giant brogmoid.
- Sealed Room in the Middle of Nowhere: At one point you drop down a hole, into a prison cell with four bricks walls and no way back up. The only way out is up but it's too high. The Jester shows up and offers to rescue you only if you can solve his riddle. Though you have infinite chances to answer.
- Stock Puzzle: This game makes extensive use of stock puzzles, though usually with a twist. Some of the puzzles include:
- Fox-Chicken-Grain Puzzle: Though you must locate the three ingredients elsewhere in the game first - and never leave them alone together, or render the game Unwinnable.
- Game of Nim
- Knights and Knaves: Only with a third participant. In addition to the Veritassi, who always tell the truth, and the Prevaricons, who always lie, there are the Wishyfoo who alternate between the truth and lies.
- 3 + 5 = 4: One puzzle involves obtaining 6 "gloops" of water using a 9-gloop vial and a 4-gloop vial. Obtaining the 4-gloop vial is a multi-stage puzzle in itself.
- Towers of Hanoi
- Take a Third Option: When faced with an executioner, every inmate gets a last request. If the executioner can do it, he hangs you. If he can't do it, he beheads you. When it's your turn, the correct request is "executioner, cut my head off." So he'd have to cut your head off, then hang you. But he's only supposed to cut your head off if he can't do it, and you wouldn't have a head or neck anymore to be hanged from... It's such a Logic Bomb that the executioner eventually gets upset and has you tossed out. If you go back in later, the executioner has come up with a third execution method just for wiseacres like you, so you can only do this once.
- Thieving Magpie: In Antharia, birds will steal your light sources from your very hands, leaving you without a light source when you enter an important cave. However, since they can only steal one a turn, you can enter the cave safely as long as you bring two light sources.
- Trickster Mentor: The Jester, who in addition to playing irritating practical jokes on you like his inspiration the Wizard of Frobozz, frequently delivers important items (like the funny paper) that you would presumably have had no way to obtain on your own and runs you through puzzles to test your resourcefulness and clarity of thinking.
- We Have Reserves: Stonewall Flathead routinely took 90+% casualties in his military campaigns (Usually suppressing riots protesting the 90+% tax rate), only keeping his troop levels up through conscription.
- Weird Moon: The phases shown in the Flathead Calendar show more unusual ones than normal ones, such as Grue Moon, Large Moon, Fast Moon, and Pac Moon. One phase is even called Weird Moon; it's an amorphous blob.
- Where It All Began: At the conclusion of the game, Megaboz's curse transforms the kingdom into the dungeons explored in the main series, with the final location being West of House (mailbox and all), the starting location for Zork 1. Despite the location, the game is not an Immediate Prequel, as the player character of this game is not the same person as the original trilogy.