to work around a potential situation where the player could irretrievably drop an object into a wall space. To develop the plot for the game, Robinett worked with Steve Harding, the author for nearly all Atari 2600 game manuals at that time. Harding developed most of the plot after playing the game, with Robinett revising elements where he saw fit. Robinett states that he had come up with the names for the three dragons and offered a friend's suggestion for naming the bat "Knubberrub". Robinett submitted the source code for Adventure to Atari management in June 1979 and soon left Atari. Atari released the game in early 1980. Easter egg Generally defined as a "message, trick, or unusual behavior hidden inside a computer program by its creator", the Easter egg concept was popularized by Adventure, influenced by the corporate culture at Atari. After Atari's acquisition by Warner Communications in 1976, there was a culture clash between the executives from New York, and the Californian programmers who were more laid back. Atari removed the names of game developers from their products, as a means to prevent competitors from identifying and recruiting Atari's programmers. This also was used as a means to deny the developers a bargaining chip in any negotiations they may have with management, according to Robinett. These attitudes led to the departure of several programmers; notably, David Crane, Larry Kaplan, Alan Miller, and Bob Whitehead all left Atari due to lack of recognition and royalty payments, and formed Activision as a third-party 2600 developer, making many hit games in competition with Atari. Unknown to anyone else, Robinett embedded his name in his game in the form of a hidden and virtually inaccessible room displaying the text "Created by Warren Robinett", inspired by popular rumors that the Beatles had hidden messages in songs. In 2015, Robinett recalled the message as a means of self-promotion, noting that Atari had paid him only around US$22,000 per year without any royalties, while Atari would sell one million units of a game at US$25 apiece. This secret is one of the earliest known Easter eggs in a video game. Robinett kept the secret for more than one year, even from all Atari employees. He was unsure of whether it would be discovered by other Atari personnel prior to publishing. It is not mentioned in the game's manual, as the manual's author was unaware. After