Editing Defender (1981 video game) (section)

=== Later development ===
By July, development was behind schedule and Jarvis's superior began to pressure him to finish the game in time for a then-upcoming trade show, the AMOA, in September. Jarvis spent several weeks creating the astronauts, which his boss felt should be omitted if the process didn't speed up. The pressure frustrated him to the point he considered resigning. Around that time, a new programmer named Sam Dicker was hired.<ref name="Ultimate"/> He assisted in programming the game and added visual and audio effects.<ref name="Ultimate"/><ref name="RG-55"/> For example, Dicker implemented a particle effect [[algorithm]] to generate unique explosions for destroyed enemies.<ref name="RG-55"/> The new elements re-invigorated Jarvis, who felt the project began to show promise.<ref name="Ultimate"/>

Development then shifted focus to the enemies. Landers were given the ability to capture humans, and a new enemy was devised from the mechanic: "Mutants", captured humans that had turned hostile. The Mutants added a rescue element to the game that Jarvis believed made it more interesting to players and encouraged them to continue playing. The element of making a "comeback" from a dire situation was applied to the planet as well. Jarvis felt it mimicked the ups and downs of real life. "Bombers", enemies which release floating bombs on the screen, were added next. More enemies were added to create different gameplay elements. "Swarmers" and "Pods" were designed to attack the spaceship as opposed to the astronauts. "Baiters" were included to add pressure to the player by preventing them from lingering. The enemies quickly follow the spaceship to collide with it, and were based on a similar enemy in ''Asteroids''.<ref name="RG-55"/>

By September, the game was still unfinished, and almost every Williams programmer assisted in meeting the deadline for the AMOA trade show.<ref name="Ultimate"/><ref name="GS-Hall">{{cite web| url = http://archive.gamespy.com/halloffame/may01/defender/| title = Hall of Fame: Defender| publisher = [[GameSpy]]| first = David| last = Cuciz| date = May 2001| access-date = 2009-12-06 |url-status=dead |archive-url=https://web.archive.org/web/20050112002131/http://archive.gamespy.com/halloffame/may01/defender/ |archive-date=2005-01-12}}</ref> The evening before the trade show, the arcade cabinets were delivered for display.<ref name="Arc-Treasure-1"/> The developers, however, forgot to create an [[attract mode]] (an automated sequence designed to entice an audience to play) and high score system for the game, and began working on them that night. DeMar coded the attract mode, Dussault and Dicker created the high score table, and Jarvis [[playtested]] and fixed bugs.<ref name=NGen38>{{cite magazine |title=Are You a Hardcore Gamer? |magazine=[[Next Generation (magazine)|Next Generation]]|issue=38|publisher=[[Imagine Media]] |date=February 1998|pages=47–48}}</ref> Early the next morning, the team created the final [[EPROM]] chips for the mode and installed them in a cabinet. The chips were put in backwards, causing an [[electrical short]] when the cabinet was turned on, so the team had to quickly burn a new set of EPROMs.<ref name=NGen38/> Once the attract mode was operational, Jarvis and the team returned to their homes to prepare for the show.<ref name="Fever"/> After the show, the developers expanded the game to allow users to play indefinitely. The display model featured five levels, which the team felt was more than enough because of the game's difficulty. Most Williams employees could not progress past the third level and Jarvis's score of 60,000&nbsp;points seemed unbeatable to them. The developers decided it was best to be prepared for players that might exceed their expectations and added more levels that repeated.<ref name="Arc-Treasure-1"/>