I wrote this program with Turbo Pascal on my trusty old 386. It had a few amusing features/idiosyncrasies:

• Sprites were hand drawn in a grid book to get the coordinates and then plotted into an onscreen buffer at run time (if you really slow down the clock speed you can see them draw at start up).
• Assembly to do the vertical re-trace, this seems a bit trivial now, but at the time was something of a coup.
• No concept of changing clock speed with amusing results on newer machines
• X-Wing inspired shields.