What it had unlike other games, however, was its selling point: an internal world editor. Simply by pressing the "E" key on the main menu, the player could begin creating their own worlds. Not only could they place all the items, creatures, terrains, and other elements they saw in the official worlds, but they could use a simple scripting language, ZZT-OOP, to program "objects" to do whatever they wished. The combination of ZZT's abstract graphics and ease of use allowed players of any age group, from children to adults, to create and share their own games regardless of skill level, contributing to its explosive success in the shareware era.
Its technological simplicity also contributed, and was an early, somewhat accidental example of "designing for the broadest hardware spec" - the game's only real requirements were 512KB of system RAM, 2 megabytes of hard drive space, the ability of the PC to run in 16-color, 25-line, 80-column text mode (which was generally standard on any graphics adapter from EGA on), and the ability to run MS-DOS 5.0 - which, generally, meant a 286 or better. In practical terms, this meant that any PC from five or six years prior to the game's release, from basically the PC-AT on, could run the game, at a time when PC games tended to push hardware rather than work on compatibility with older hardware, and when PC hardware was evolving explosively. The ability for basically anyone to play the game if they'd purchased an IBM-compatible in most of the prior decade was deeply appreciated by many users and contributed to the game's (comparatively) huge sales in the early 1990s.
The success of ZZT was such that it allowed Tim Sweeney to fund further game development, and build up his company into what is today known as Epic Games. Decades after its peak, ZZT, now freeware, maintains a small but healthy community of both enthusiasts and new creators alike, creating new worlds to this very day. External editors such as KevEdit and ZEdit2 now make it easier than ever to make new games for the engine, and the emulator Zeta allows the game to be played on modern computers, including in your web browser. In 2020, a fan reverse-engineered ZZT to reconstruct its source code, which Sweeney admitted to have lost, and released the result under the MIT License with his blessing as "The Reconstruction of ZZT", allowing anyone to create their own fork of the engine customized to their liking. The Museum of ZZT is the current hub of the community, dedicated to not only documenting the game's history (with over 3,000 games hosted as of this writing), but publishing new worlds.
A sequel, Super ZZT, was released in October 1991, with new features such as an expanded board size, a scrolling viewport, special "stone" items that enable custom HUD displays, and the ability to place items in more colors than what the ZZT editor could provide without fanmade workarounds. However, it fared worse than its predecessor on account of its squished display and the fact that the editor was locked away by default unless the user ran the game with the command line argument "/e". Even now, there are much fewer Super ZZT worlds compared to ZZT worlds, though it is slowly growing as the years go by.
General tropes associated with the engine:
- Alien Geometries:
- The target boards (screens) whenever you walk off a board in each cardinal direction are only defined for that specific board. This means a designer can make one board link to another, but then have the second board either not link back to the first or even link to a different board altogether, allowing for non-Euclidean level design. It's also possible to make a board loop in on itself for extra effect.
- In older worlds, it was more common for this to happen by accident, because the built-in editor does not automatically link boards when you connect one board to another. This means you need to set both ends of the exit individually, or else you can end up with a one-way exit that can often render a world Unintentionally Unwinnable. By contrast, modern editors will link board exits by default, and even indicate if the board exits reciprocate (with a command or option to either fix it if they don't, or undo it to invoke this trope).
- ASCII Art: By virtue of running entirely in text mode.
- Beating A Dead Player: If you die, the game's animation speeds up and any enemies and traps on the screen will continue attacking your icon at superspeed.
- Blackout Basement: Some screens are dark, requiring the use of a torch to have limited sight.
- Dialogue Tree: These feature in the official worlds, and the user can create their own using ZZT-OOP, scripting both the possible responses and what they will do.
- Fun with Acronyms: Though ZZT didn't originally stand for anything, it has been joked that it means "Zoo of Zero Tolerance".
- Game Maker: The world editor and the ZZT-OOP scripting language effectively makes the game into this.
- Interchangeable Antimatter Keys: Mostly - keys come in 7 colors, but if you already have one key, another key of the same color cannot be collected and will instead block your path. Many puzzles are deliberately centered around this behavior.
- Level Editor: Most people agree that this is the best part of the game (much to the surprise of the game's creator).
- Locked Door: Locked doors with colored keys are a puzzle supported by the engine by default. If you don't want the defaults, of course, you can use ZZT-OOP to script your own.
- Nintendo Hard: The official worlds tell you from the start that you'll need to save a lot.
- Power Up Motif: Collecting an energizer (which provides temporary invincibility) causes the player to flash and also plays a jaunty tune—an arrangement of the Surfaris' "Wipeout". When the tune finishes, the energizer effect also stops.
- Respawn Point: Some rooms are set up so the player warps to where they entered whenever they are hurt.
- Space-Filling Path: Ping Pong Paths appeared so frequently in older and lower-quality games that numerous "help" worlds designed to help with game development urged designers not to use them. ZZT Syndromes in particular forces the player to step on all the tiles in a Ping Pong Path to emphasize this until the tutor lets you off the hook by carving a path straight through it.
- Timed Mission: Individual levels ('boards') can limit the amount of time a player can spend on them and send you back to where you entered if it runs out.
- Ten-Second Flashlight: The torches, which only last for a few seconds before burning out.
- Unwinnable: it's possible to end up in e.g. a position where you need ammunition, but with none left.
- Xtreme Kool Letterz: The name ZZT was chosen so that it would appear on the bottom of Usenet listings.
Tropes associated with the four official worlds:
- Bilingual Bonus: The jail in City of ZZT includes a prisoner who only speaks Spanish. Translating it reveals an admission from Tim Sweeney that he's not good at writing in Spanish.
- City Noir: The eponymous City of ZZT is introduced as the "home of smog, crime and endless bureaucracy", which is why you must escape from it. On top of that, the city is filled with all manner of deadly obstacles and the mayor is openly corrupt.
- Corrupt Politician: The Mayor of the City of ZZT will not help you unless you give him a 100-gem bribe to fund his re-election campaign.
- The Devil Is a Loser: In Caves of ZZT, saying "yes" to the Devil's challenge causes him to give up without a fight.
- Excuse Plot: Town and Caves amount to, "explore this place and collect the purple keys", while Dungeons is "you've been thrown into the dungeons, collect the purple keys to escape". City is "this city is awful, get a key and ticket for the next train out of town".
- Heroic Mime: The player has no dialog in any official game.
- Invisible Monsters: Traversing through Hell in Caves of ZZT requires fighting an invisible demon.
- Locked Door: Town, Caves and Dungeons revolve around collecting purple keys to open the doors to the final area. City requires only a single purple key, but you need some other items to board the train as well.
- Kleptomaniac Hero: Collecting one of the purple keys in Town of ZZT requires the player to rob a bank. They also cannot access the Stock Room in the Armory unless they trick the Guardian of the Key into shoving their key out the door so they can steal it.
- Oddball in the Series: City of ZZT is the only official world that does not involve collecting purple keys to reach your goal; instead, you must collect a variety of other items to enable your escape from the city by train, courtesy of the engine's flag system. It also makes the heaviest use of ZZT-OOP in general, including a puzzle that involves piloting a robot with a separate control panel, while the other worlds make only minor use of scripting in comparison.
- Schmuck Bait: The Alpha in Dungeons of ZZT is preceded by a series of one-word scrolls saying, "If you touch the Alpha, you will die", which is exactly what happens.
- Shout-Out: Asking the Vendor in the Town of ZZT Armory for "Advice" will result in them quoting "Stairway to Heaven" by Led Zeppelin.
- To Hell and Back: In Caves of ZZT, the player must go to Hell to get one of the purple keys, and then escape with their life.