Lebling returned, adding features and iterating on the parser through June 1977. Grues were added to replace pits that would kill players in the dark; while play-testing, Lebling noticed that his character fell into a pit while in the attic of the house. Lebling contends that Adventure was one of Zorks only influences, as there were few other games to emulate at the time. Although the game's combat is based on Dungeons & Dragons, Lebling said the other developers had never played it. He also thought of the parser and associated text responses as taking on the role of the Dungeon Master from a Dungeons & Dragons game, trying to lead the player through a story solely by describing it; this had also been the idea behind the parser in Adventure. Creation The developers did not announce their game while it was in development, but a lack of security on the MIT systems meant that anyone who could access the PDP-10 computer over the ARPANET could see what programs were being run. As a result, a small community of people, many of whom had been involved in playing and contributing to Trivia, would "snoop" on the system for new programs. They found the new "Zork" adventure game and spread word of it under that name. This communitydozens or possibly hundreds of players, according to Leblinginteracted with the developers as they created the game, playtesting additions and submitting bug reports. The implementers added a command transcript feature to keep track of what commands players tried to use unsuccessfully. By the end of June, the game was approximately half the size of the final Zork, and had a substantial community of players for the time. The group added locations such as a volcano and coal mine, and soon shifted their efforts to improving the game's engine and adding the ability to save the player's progress in the game. Following user requests, they also added the ability for the game to run on PDP-10 computers running different operating systemsTENEX and TOPS-20which were much more popular than the Incompatible Timesharing System operating system the MIT computer used. These users then set up a mailing list to distribute updates to the game. The developers returned to creating new content in the fall of 1977, adding the "Alice in Wonderland" section and a system for fighting enemies. Around this time, community member Ted Hess at DEC