enjoyed the game and similar titles, he was dissatisfied with the control scheme; Berzerk used a single joystick to move the on-screen character and a button to fire the weapon, which would shoot the same direction the character was facing. Jarvis noticed that if the button was held down, the character would remain stationary and the joystick could be used to fire in any direction. This method of play inspired Jarvis to add a second joystick dedicated to aiming the direction projectiles were shot. Jarvis and DeMar created a prototype using a Stargate arcade system board and two Atari 2600 controllers attached to a control panel. In retrospect, Jarvis considers the design a contradiction that blends "incredible freedom of movement" with ease of use. The developers felt a rescue theme similar to Defender—one of their previous games—was needed to complete the game, and added a human family as a method to motivate players to earn a high score. The rescue aspect also created a situation where players had to constantly reevaluate their situation to choose the optimal action: run from enemies, shoot enemies, or rescue humans. Inspired by George Orwell's Nineteen Eighty-Four, Jarvis and DeMar worked the concept of an Orwellian world developed into the plot. The two noticed, however, that 1984 was approaching, but the state of the real world did not match that of the book. They decided to set the game further in the future, the year 2084, to provide a more realistic timeframe for their version of "Big Brother". Jarvis, a science fiction fan, based the Robotrons on the idea that computers would eventually become advanced entities that helped humans in everyday life. He believed the robots would eventually realize that humans are the cause of the world's problems and revolt against them. Jarvis and DeMar playtested the game themselves, and continually tweaked the designs as the project progressed. Though games at the time began to use scrolling to have larger levels, the developers chose a single screen to confine the action. To instill panic in the player, the character was initially placed in the center of the game's action, and had to deal with projectiles coming from multiple directions, as opposed to previous shooting games such as Space Invaders and Galaxian, where the enemies attacked from a single direction. This made for more challenging gameplay, an aspect Jarvis took pride in. Enemies were assigned to