I don't know if I've ever met someone who actually played Prime Directive. Someone needs to put you in a museum!
My Parents and grandparents were/are hoarders... I feel like I'm living in one already.
PD was/is a solid game - the core mechanic is a d6 dice pool, 6=5+1d6, recursive; except on initiative, read only the highest die. Compare it to a 3 number difficulty, default being 4/6/8. Beat the low? minor success/partial success, beat the mid, moderate success, beat the high, complete success. Many things a minor is "Didn't get it done but can continue to work" while moderate is usually good enough.
Dice pools are average of skill and linked attribute; if no skill, there's also a difficulty penalty.
The complexities:
Initiative: best die determines action level. Each die individually contributes to initiative number: minors 1, moderate 2, complete 3, crit 5, fail/botch 0.
Optional Additional difficulty levels: under half minimal is a botch. twice or more the complete is a crit.
Scatter Phasers... just about all aspects of them in play. Massive power use, area affect...
Character gen is overlapping templates (species, starfleet, division, specialty)- my play notes reduce this to race and specialty by doing the fixed element combinations)
Both wound and stun damage. And stun overflow to wounds. And penalties from both.
Not all skills use the default 4/6/8 difficulty - some are 2/4/6, a few are 6/8/10. Skills that should be harder to learn have higher base difficulties., and vice versa. A table of these is handy in play.