The NPPC System is nearly the same as the PC generation system in the _2300 AD Adventurer's Guide_. There are a few different steps, but the results are much the same. Thus, the name: The Non-Player Player Character System.
GDW provided a great little system for quick NPC generation: You assign any physical characteristics that you like, draw two cards to determine a main and a secondary motivation, choose a career, and a level of "Green", "Experienced", "Veteran", or "Elite". The latter determines all skill levels, while the career determines the skills. This works well for quick NPC generation, but it has some problems...
Suppose that your PCs are driving along in their vehicle, when it breaks down. They stop and try to fix it, and even with the proper tools and spare parts, are too low in skill to succeed. They walk into the nearest town, looking for a garage, and hire a tow-truck to come out and haul them in, and then expect the garage owner to fix it. Even with the one level decrease in difficulty (for not being in the field), the poor Mechanic can have a maximum Mechanics skill level of 3, with the GDW system, above... and that's if he's Elite!
So, if you have any "Mr. Fix-Its" among your players, he'd stand a better chance of fixing the vehicle, himself, using the Mechanic's lift, than the poor NPC mechanic would! How do we "fix" this "problem"? Fear not! It's really pretty easy, although it involves modifying the GDW system, a bit.
If the above situation is a random encounter, simply increase the mechanic's skill to a sufficient level, and roll against it. You can always say that his skill in some other area is undeveloped, so that he could concentrate on auto mechanics.
On the other hand, if this NPC is someone that the PCs will be running into on a regular basis ("What? You boys broke the transaxle again? Where have you been driving this thing, the badlands?"), then it makes sense to develop the character more thoroughly! Here's how I handle it:
First, I use the Homeworlds Determination Table to figure out which world an important NPC is from (if the players are on Aurore and I want to generate an Auroran, it's even easier). This also tells me the nationalities that the NPC is most likely to be, as well as the gravity type they were born under, and a maximum age. Unless I have a good reason to pre-determine something, I roll stats, body type, etc., randomly. Note that, unlike "quick" NPCs, this also gives them Consciousness/Life Levels, just like PCs have. Some players may be stunned when an NPC takes more than three Stun Points or Light Wounds, before becoming incapacitated!
Next, I choose Background Skills (based on Education), just as PCs do. In the case of the Auto Mechanic, above, I would put quite a few into Ground, Hover, and Sea Vehicles, as well as Electronics and Mechanics. All of this information should be recorded on a Character Sheet.
Next, I figure out what role this NPC is supposed tp play in the campaign, and what skills they need to do it. This determines the one or two careers the NPC will enter. In the Mechanic example, I would choose the Repairman Career, as an obvious choice. Once the career is chosen, skills are selected, just as PCs do it. Turning points must also be passed, in the same manner.
When done, the Referee has a complete NPC, complete with skills, careers, NPC motivation results, Hair/Eye Color, languages known, nationality, and a bit of work history. As an added benefit, the PCs won't be able to figure out as much about the NPC without interaction, as they have in the past! ("Yep, he's got Combat Rifleman 1, so he's just an experienced NPC. He'll have all the other Military Skills at Level 1, and since he's Ground Military, he'll have Ground Vehicles skill, too.") Now the poor PCs will have to ask you what skills your NPC has... My usual answer is "Why don't you have your PC ask him?" This encourages role playing.
As an added benefit, if some PC becomes hors de combat, or you have a curious friend drop by unexpectedly for the evening, you can pass this fully developed PC into their lap, and announce: "You guys remember Pumper, the Mechanic who's been fixing up your vehicles? Well, she shows up on your doorstep, one day, and tells you `the authorities' have closed down her shop, and she's suddenly decided that she might like to join your team..." (anyone smell an adventure, finding out why Pumper's station was shut down, trying to get it re-opened, fighting the French Bureaucrats, and having someone new who's good at fixing things (but lousy at combat) join the PCs?). You get the idea...
Also, if you need some quick, basic equipment for either a "quick" or a NPPC NPC, just add the roll of 1D10 to the number of years in a career (doing it twice, if they had two careers), and look the results up on the appropriate Career Benefits Table. This will give you a quick list of stuff that the NPC may have handy.
So, for quick NPCs that your characters won't remember interacting with, you can always use the "quick" NPC System that GDW gave us. For the major baddie of the campaign, however, use the NPPC system. Pick his/her Homeworld, body type, maybe even some stats to fit the plot. If they are from an Extra-legal career, go ahead and determine randomly (on the Benefits Table) whether or not they are wanted by the law. Choose their NPC Motivation Cards to suit. Anything you don't care about can be rolled.
By doing this, and picking your NPC's skills carefully, you will find the game enriched. Who would choose to make an NPC a Korean from Lachesis? No one I know of, but by rolling randomly for Homeworlds, such odd results can come up! This enriches the campaign, and adds a little more color to a predominantly French/German/English Arm.
The NPPC system is best for occassional use (although you could use it every time, if you don't mind a lot more work), and will help to keep your characters guessing. Is that Thief a random encounter, or is he a carefully planned NPPC? Will his mug-shots appear in the books, down at the local police station? Is there a reward? Maybe this random encounter is really the beginning of a brand new adventure, that will carry the PCs, willy-nilly, into the heart of the Chinese Arm! Who can say?