The basic gameplay of Robotron was most inspired by the Berzerk arcade game, which we discussed in the book's Chapter 2, "Castle Wolfenstein (1981): Achtung! Stealth Gaming Steps Out of the Shadows."
According to Jarvis, "I was a great fan of the game Berzerk, and the frustration of that and all other single-joystick games was that you have to move toward an enemy in order to fire in that direction. Berzerk had a mode that alleviated that somewhat in that you held the fire button down, the character would stand still and then a bullet could be fired with the joystick in any direction. So essentially in that mode the joystick fires the bullet. I just put on a separate joystick to fire bullets."
Jarvis toyed with the idea of a more passive game with no firing, where you would kill the robots by making them walk into Electrodes, but soon realized that this was not the path to gaming enlightenment:
"It was fun for about fifteen minutes, running the robots into the electrodes. But pacifism has its limits. Gandhi, the video game, would have to wait; it was time for some killing action. We wired up the 'fire' joystick and the chaos was unbelievable. Next we dialed up the Robot count on the terminal. 10 was fun. How about 20? 30, 60, 90, 120! The tension of having the world converge on you from all sides simultaneously and the incredible body count created an unparalleled adrenalin rush. Add to it the mental overload of a truly ambidextrous control, and it was insanity at its best."
The Atari 5200 received the only home conversion of Space Dungeon. The addition of the pictured joystick coupler made the experience more authentic and also worked great with the Robotron: 2084 cartridge.
The result was that Robotron was one of the very first, all-out, nonstop action games that truly resonated with the general public. Though unforgiving in its intensity and requiring an almost Zen-like state-of-mind to rack up a respectable score, the game was perhaps the first evolution of that elusive "perfect" twitch game, an all-you-can-kill buffet.
The nonstop action and wave after wave of enemies were balanced by the basic human need to nurture, in the form of rescuing the Humanoids. It perhaps speaks even more pointedly to the human condition that death is inevitable and unavoidable, as in the arcade classic nuclear missile defense game, Missile Command (Atari, 1980).
Box back for the Atari 8-bit version of First Star Software's Astro Chase, which offered what it claimed was revolutionary "single thrust propulsion," but was really just an option for the player to lock in a movement direction while firing in another. It was a nice concession to the limitations of home controllers, but still not an ideal replacement for the preferred Robotron dual joystick control scheme.
As described briefly in book Chapter 18, "Super Mario 64/Tomb Raider (1996): The Third Dimension," it wouldn't be until the idea (or discovery) of using dual analog sticks to control 3D games became an option in the late 1990s -- often using one stick for movement and the other for aiming or camera control -- that using two controls simultaneously became common practice.
Prior to that, dual, simultaneous controls were used sparingly outside of the arcade, for mostly practical reasons. As stated by Jarvis, "Robotron has always been frustrating in non-arcade versions because of the lack of the dual-joystick control. Because of the intensity of play the game is very athletic, and it is very nice to have a 300-pound arcade cabinet stabilizing your joysticks. Without true dual fixed joysticks, the game can be quite frustrating in console and PC versions."
A scene from Bally Midway's arcade game, Tron, based on the cult favorite movie. Gameplay consisted of various scenes, including Light Cycles, MCP Cone, Tanks, and the pictured Grid Bugs. Tron made simultaneous use of a spinner and a joystick with a fire button trigger.
Nevertheless, home versions of Robotron-style dual-control games typically took one of two basic approaches to the challenge. Some games, like the home translations of Vanguard, would simply combine movement and firing into one controller -- where you moved, you fired. This typically changed the basic gameplay. In the case of Vanguard, the arcade player was able to move with the joystick and fire separately in one of four cardinal points with the buttons.
 Other suggestions either from Jarvis himself or others include Chase on the Commodore PET computer and Robots for UNIX, each of which shares similarities with the later Berzerk.
 More or less after the release of Sony's DualShock in 1998 for their PlayStation console.
 That is, outside of the mostly first-person shooter computer games from a few years earlier. Their interfaces eventually developed into the now-common mouse/keyboard combination. See book Chapter 5, "Doom (1993): The First-Person Shooter Takes Control," for more on this.
 A 1981 Centuri release in the arcade, and a 1982 Atari release for the Atari 2600 VCS and 5200. The home versions would also allow the player to shoot forward continuously if they so chose.