A strange little side quest
Zoom out from Z Defense for a moment and the timeline gets surprisingly deep. Games resembling checkers were being played thousands of years ago; evidence of related games reaches back to around 1600 BC. A second detail makes the picture even better: Gun Fight reached arcades in 1975 and became the first arcade video game to use a microprocessor. So a round of Z Defense is not just a quick distraction; it is a tiny stop on a much longer strategy games timeline.