In a column for Gamasutra, game designer Manveer Heir stated, "In 1977, the Atari 2600 [Video Computer System (VCS)] was launched with a joystick that had a grand total of one button to use.

Today, the [Microsoft] Xbox 360 has sixteen buttons on their controller. In other words, about every two years, we get another button on our controllers.

This increase in interface complexity is the result of increased game complexity." Heir's statement is all too true, and is likely one reason why older games with simpler requirements and demands have regained popularity in recent years.

However, although Defender was not an easy or simple game, it was still converted to the Atari 2600 in a high-profile 1981 release that -- along with Space Invaders (1980) and Asteroids (1981) -- helped the system become a dominant platform.

Besides an obvious reduction in sound and graphics -- the arcade version's mountains turned into blocky city buildings -- the control scheme was also modified to fit the platform's constraints.

The 2600's single-button joystick had to accommodate the arcade version's up/down joystick and individual Reverse, Hyperspace, Smart Bomb, Thrust, and Fire buttons. This change in control scheme results in distinct changes in both gameplay and flow.

The Atari 2600 version of Defender took many liberties with the license.

Unlike the arcade version, in which two or more Landers can kidnap Humanoids simultaneously, the 2600 version allows for only one at a time. Also, Humanoids can't be accidentally shot by the player and Hyperspace never results in instant death, as occasionally happens in the arcade version. Finally, the joystick in the 2600 version is used for all movement and thrust, and the single fire button is used to fire lasers, release Smart Bombs, and activate Hyperspace.

Smart Bombs are activated when the button is pressed when the ship is at the very bottom of the screen (behind the city) and Hyperspace at the very top (behind the minimap), making their overall utility questionable at best. A final result of the game's concessions to the home platform is that every time the player fires, the Defender ship disappears (essentially, one graphical image would replace the other), creating unintended possibilities for evading enemy hostility.[4]

A later 2600 game inspired by Defender's gameplay is Bob Whitehead's Chopper Command (1982) for Activision. Whitehead kept the 2600's limitations in mind, and featured the type of audiovisual polish that distinguished the company on the platform.

Although not a particularly ambitious game in terms of mechanics, it nevertheless succeeded by being a highly playable, straightforward shooter that utilized the same type of minimap, inertia-based movements and high difficulty from Defender, albeit with the notable omission of the rescue component. In Chopper Command, the player is simply tasked with using his or her helicopter to defend a truck caravan from bomber jets and other helicopters.

Chopper Command was Activision's strictly action-oriented answer to Atari's conversion of Defender for the Atari 2600.

Dan Gorlin, on the other hand, with his much ported Choplifter (Broderbund, 1982; Arcade [Sega], Atari 7800, Coleco ColecoVision, and others) for the Apple II, made one of Defender's best features a critical component of his classic helicopter-based hostage rescue game. In an interview for the book Halcyon Days, Gorlin describes how the design for Choplifter developed from Defender a bit differently than one might expect:

"Being fascinated with helicopters, I started out by making one fly around using a joystick. It was really cool, so I kept adding things to shoot at. We had this local kid doing some repairs on my car just outside, and he used to come in and play with it. He was a big Defender freak, and one day he said, 'You should have some men to pick up.' I walked over to the laundromat and took a closer look at Defender to see what he was talking about -- never played it myself -- and damned if I could see any men, but took his word for it, and it seemed like a cool idea."[5]

Back of the box for the Coleco Adam The Best of Broderbund: A.E. and Choplifter, the former a type of Galaga clone (see Chapter 16, "Space Invaders (1978): The Japanese Descend") and the latter inspired by Defender.

[4] Other home ports generally kept most arcade features intact and allowed for more robust control schemes consistent with the target platform.

[5] See http://www.dadgum.com/halcyon/BOOK/GORLIN.HTM. Unlike in Defender, the tiny humans in Choplifter were easier to identify and better animated.