i played z66 and it must of been a very long time around at least 13 years ago at least it came out on a disc of 100 games that run on both dos and windows and it was a complete mix, corridor 7, zone 66, commander keen, adventure, Animal adventure, apples and oranges. mostly epic megagames and apogee related, dark blue disc.
zone 66 was one of the odd balls next to trolls where the objective was not really known, however on zone 66 1d sideways scroller only its not one way like flying tigers or galactix. the controls are wierd at first however you get used to them, i did manage to clear out most the enemy structures and the hundred or so enemy fighters, including that purple boomerang with the 4 thrusters and that blue triangle (triangle ship again!!). i suggest you go for the big green fighter later, however start off with the small jet fighter to chase the enemy fighters off, go land and change load out, if you can fly to the nearest landing pad closest to the next enemy structures, advisable instead of landing opposite end of the map from your objective otherwise you will run out of fuel.