As a teenager I used to love watching people play Defender on the arcade machines but I didn't have the money to play so it could never became an addiction. A few years back I built my own MAME arcade cabinet to play the game (and others). It turned out I was completely useless at the bloody game
Defender in the arcade was tough. I never really got used to the reverse and thrust buttons to control lateral movement. But I played it a lot on my Atari 1200XL, where the joystick controlled the direction and speed as well as elevation.