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ZZT Title screen.gif
Title screen of Episode 1
Developer(s)Potomac Computer Systems
Publisher(s)Potomac Computer Systems
Designer(s)Tim Sweeney
Genre(s)Action-adventure, puzzle

ZZT is an action-adventure puzzle video game developed by Potomac Computer Systems and released for MS-DOS in January 1991. The game was designed by Tim Sweeney and took roughly nine months to develop, including the game's scripting language, ZZT-oop. ZZT was followed by a sequel, Super ZZT, in 1992.

The game's name was picked so it would be listed last alphabetically in shareware catalogs and on bulletin boards, and a fan later suggested the backronym of "Zoo of Zero Tolerance", which Sweeney endorsed.[2]


The player character is controlled by the four cursor keys, and the shift key and a cursor key pressed will shoot a bullet (if the player has ammo). Items that can be picked up include: ammo (each magazine holds five rounds), gems (used for currency in most games), torches (used by pressing the T key in darkened rooms, lighting a small area around the player, that moves as the player does), scrolls (display a message, usually), and energizers that give the player temporary invincibility. Enemies include lions (randomly moving monsters that may follow the player), tigers (randomly moving monsters that fire bullets), ruffians (monsters that chase the player, then rest, then repeat), bears (chase the player when near by, otherwise staying still), slimes (spreads out across the screen), centipedes (consisting of several segments linked together, walks as a group), sharks (move around in water), and spinning guns (stay still and fire bullets). There are many other objects in ZZT, too.


Video game programmer Tim Sweeney, at the time attending the University of Maryland, first developed ZZT as a text editor that ran in Pascal.[3] However, after experimenting with ASCII characters, Sweeney designed his first levels for what would become the video game. The game took around nine months to develop,[4] and was released in January 1991.[1]


Critical reception[edit]

Third-party worlds created for ZZT were diverse, ranging from shoot 'em ups to complex role-playing games to a Lemmings clone, Zem!.[5] Other games have been inspired by ZZT, such as MegaZeux, Frog Fractions 2 and ZZT's sequel, Super ZZT, the latter being widely criticized for lacking an easily accessible editor function, which was a mistake on Sweeney's part.[2] Computer Gaming World billed ZZT as the first major video game to use object-oriented programming.[6]

Although Super ZZT is in many ways a vast improvement over ZZT, it never caught on with the ZZT community like the original ZZT did, and very few games were ever created for Super ZZT.[4]


Following ZZT's release, the game sold about three to four copies daily, and as of 2009, had sold around 4,000 to 5,000 copies in total.[3] After Sweeney moved out of his parents' house to establish proper corporate headquarters for Potomac Computer Systems, then renamed Epic MegaGames, his father, Paul Sweeney, continued fulfilling mail orders to the original address under the "Epic Classics" label.[7] The final copy of ZZT was shipped to game designer Zack Hiwiller in November 2013.[7]

Around 1992, after the custom world design contest, copies of the "ZZT's Revenge" collection was on sale with "Best of ZZT" shipped with it for free.[8]


Shortly after the release of ZZT, Sweeney started a level designer contest for registered users to make their own worlds and submit them to him.[9] Over 200 users submitted their custom worlds. The best collaboration games that won the contest were The Best of ZZT and ZZT's Revenge. The winners of the contest received prizes of gift certificates. The six winning custom worlds that made up ZZT's Revenge earned the designers employment in Epic MegaGames. Other contestants got honorable mentions for good entries.[8]

Around 1992, Sweeney started a contest titled "ZZTaholics Challenge" for players to play any of the ten volumes from ZZT, ZZT's Revenge and Super ZZT, then submit their high scores. The winners received discount coupons to get the next two releases from Epic MegaGames for free.[2]



Sweeney collaborated with programmer Allen Pilgrim on creating a sequel to ZZT called Super ZZT, which added more features and levels to ZZT's core gameplay. The game plays similarly to ZZT, and incorporates floor textures, a different gameplay menu, prefabricated enemies and objects, and scrolling map screens, allowing for much larger worlds than in ZZT.

Third-party level editors[edit]

In addition to archive websites, several developers have released ZZT world editors such as KevEdit for Windows.[10][11] The external editors would have more features such as color coding objects, fade tools, and access to STK without downloading.[12] DreamZZT was an emulator for the Dreamcast.[13]

Reconstructed source code[edit]

Sweeney claims to have lost the source code of ZZT in a crash.[3][14] To compensate for this loss, a community developer reconstructed the source code in 2020, with permission of Sweeney.[15] The reconstructed source code is binary accurate; when compiled with the Turbo Pascal 5.5 compiler an identical .EXE file is generated. The source code is released under a permissive[16] software license on GitHub.[17]

Further reading[edit]

  • Anthropy, Anna (2014). ZZT. Boss Fight Books. ISBN 978-1-940535-02-9.


  1. ^ a b Dr. Dos (January 15, 2021). "ZZT and Epic Newsletter Scans". Museum of ZZT. Retrieved January 15, 2021.
  2. ^ a b c Sweeney, Tim (1992). "Epic MegaGames Newsletter - Spring 1992". Museum of ZZT. Epic MegaGames. p. 2. Retrieved March 28, 2018.
  3. ^ a b c Edwards, Benj (May 25, 2009). "From The Past To The Future: Tim Sweeney Talks". Gamasutra. Retrieved March 27, 2018.
  4. ^ a b Hercules (November 17, 2000). "Hercules meets Tim Sweeney". DigitalMZX. Retrieved March 28, 2018.
  5. ^ Dr. Dos (August 24, 2016). "Closer Look: Zem! and Zem! 2". Museum of ZZT.
  6. ^ Circle Reader Service #12 (July 1991). "Taking a Peek" (PDF). Computer Gaming World. No. 84. p. 78.
  7. ^ a b Pitcher, Jenna (November 21, 2013). "Epic Classics ships last copy of ZZT". Polygon. Retrieved March 28, 2018.
  8. ^ a b Sweeney, Tim (1992). "Epic MegaGames Newsletter - Spring 1992". Museum of ZZT. Epic MegaGames. p. 3. Retrieved March 28, 2018.
  9. ^ Sweeney, Tim (1992). "Epic MegaGames Newsletter - Spring 1992". Museum of ZZT. Epic MegaGames. p. 1. Retrieved March 28, 2018.
  10. ^ Kohler, Chris (2006). Retro Gaming Hacks: Tips & Tools for Playing the Classics (1st ed.). Beijing: O'Reilly. ISBN 9781449303907. OCLC 607589293.
  11. ^ Dos, Dr. "Closer Look: Modern ZZT Editing With KevEdit - Museum of ZZT". museumofzzt.com. Retrieved April 17, 2018.
  12. ^ "z2". zzt.org. Retrieved April 17, 2018.
  13. ^ Carless, Simon (2004). Gaming Hacks (1st ed.). Sebastopol, CA: O'Reilly. p. 67. ISBN 9780596007140. OCLC 326649266.
  14. ^ zzt on epicgames.com "Please don't ask for the source; if I had it, I'd release it, but I lost it in a crash a long time ago." (archived in 1999)
  15. ^ ZZT's source code has been reconstructed - Reconstruction of ZZT is a game-changer for the ZZT community on retronauts.com by Stuart Gipp (March 17, 2020)
  16. ^ license.txt on github.com/asiekierka/reconstruction-of-zzt
  17. ^ reconstruction-of-zzt on github.com