photons, xylons, Star Raiders had everything! and it sounds like it was all taken from other stuff.
Yar's Revenge never made any sense and was the hardest game I had when I was a kid.
The big selling point with Star Rangers was that it came with its own controller: a keypad that you used to navigate from one screen with little blips that you shoot at and get shot at by to another screen with other little blips that you shoot at and get shot at by. Pretty progressive for its time I guess. Star Rangers was the only game the keypad worked with.