Super ZZT is the successor to ZZT, created by Allen Pilgrim and Tim Sweeney of Epic Games (then Epic MegaGames). Like its predecessor, Super ZZT was essentially a game creation system with a few games packaged with it, which included Lost Forest, Monster Zoo, and Proving Grounds. Like ZZT, the greatest draw to its sequel was the level editor which allowed players to create their own games. The editor itself was somewhat "hidden" by the creators, perhaps because it was not quite as polished as they wanted in time for the release. It was necessary to add the argument /e to the command line when loading Super ZZT, and then to press E to enter the editor.
Some changes to this version include floor textures, new prefabricated enemies and objects, and scrolling maps, allowing for much larger worlds than ZZT would allow. 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. However, notable game creation group Interactive Fantasies did create 3 Super ZZT games.
Source: Wikipedia, "Super ZZT", available under the CC-BY-SA License.