Off topic for the Prime Directive in question here, but on the broader topic of Prime Directive:
I was a play-tester for GURPS Prime Directive ground combat. I'm not sure which edition, but it had "Powered by GURPS" on the cover.
My main impression was that it modeled Star Trek combat very well; in the show, a phaser set to stun either missed or stunned normal humanoids with a single hit, and a phaser set to kill either missed or killed normal humanoids with a single hit. (On rare occasions one might get away with a nasty burn.) Of course, "Bleep! You're dead," is not much fun for gaming; "Bleep! You're unconscious," isn't much fun either.
The real fault is that Trek phasers themselves don't carry over well to gaming; in the show combat was not resolved by a die roll, but by the narrative needs of the story.
At the time I didn't have any ideas about how to make phasers work in gaming. But while recalling that play-test, I thought of this solution:
About the best way I can think of to model phaser combat is to give each character a number of "miss points". When someone shoots a phaser, they roll to hit. If the dice say hit, the player can say, "I spend a miss point", and the phaser misses.
If the player chooses not to spend a miss point, the game master reveals whether the phaser was set to stun, kill, or disintegrate. If it's set to stun, the character falls unconscious. If kill or disintegrate, the player gets another chance to spend the miss point unless the character is a red-shirt.
Such a solution isn't very true to GURPS, except for the general rule in all role-playing games that any rule can be overridden for the sake of fun. But it's a lot like the way a lot of modern story games work.
Of course, for other types of combat, GURPS works fine. Personal combat in Trek usually meant a fist fight, and GURPS is fine for that. Likewise, space combat was probably fine; hit points for damage, shields, and the ship model it well. We didn't play with it, possibly because it was working.
For those who have played GURPS Prime Directive (or read it closely), how did it turn out in print?
