[Gatac]

Okay, *very* basic d20 system explanation:

Basically, your character has an overall level, depending on how many Experience Points he/she has gained. This is a gauge of overall power level, and goes - regularly - from level 1 to 20. You can gain levels beyond that (that's called "epic"), but I have serious doubts that we'll get to that, so just forget that for now.

EXAMPLE: Ensign Ricky is on his first tour of duty. Being a starting character, he begins play as a Level 1 character. Captain Richardson, however, has seen his share of action. He's already Level 10. An "iconic" character such as, say, Captain Kirk, would probably land at Level 15 or higher.

First, you determine the race/department of your character. This grants a bunch of boni and penalties. There's some advanced options here, but for the most part this isn't rocket science.

Your character's most basic statistics are his ability scores. You have Strength, Dexterity, Constitution, Wisdom, Charisma and Intelligence. Those can go as low as 1 and have no "hard" upper limit, but 10 is generally considered "human average". A character with 18 in one score is in the top human percentile, and anything beyond that can be considered "heroic" or "superhuman". Your ability scores don't generally change much.

EXAMPLE: Ensign Ricky is a bit shy, but he's very smart. His Charisma is only 8; below average. His Intelligence, on the other hand, is 17, near the top of the normal human spectrum.

Then there's skills. There's literally tons of skills; this are things you can improve with training and such, knowledge about various topics...This is stuff like Jump, First Aid, Sleight of Hand. You get more skill points through levelling up. Your level determines how many points you can spend on a skill. Also, your skills are keyed to one ability score, and gain boni (or penalties) from that ability.

EXAMPLE: Ensign Ricky has maxed out his Demolitions skill at 4 points for his 1st level. If he gains enough experience to advance to Level 2, he could invest another point in Demolitions. Since Demolitions is keyed to Intelligence, Ricky gains a bonus from his ability score: +3. Thus, he has a total skill bonus of +7 for Demolitions at first level, and +8 at second.

Feats are more specific tricks and techniques that set you apart from the common populace; they improve skills in special ways, allow new skill uses, or in some cases completely different abilities. For example, every character can try to throw a punch, but they'll have an easier time at it with the Martial Arts feat. You gain a feat at 1st level, 3rd level, and every 3rd thereafter. Feats often have prerequisites to meet.

EXAMPLE: Ensign Ricky gets to Level 3. He gets a new feat choice and chooses Explosive Basics, which requires 5 ranks of Demolitions (which Ricky has). On the other hand, he can't choose The Look, which requires an ability score of 13 for Charisma.

There are various derived values. You have Defense (how hard you are to hit), Initiative (when you act during combat), your Base Attack Bonus (how accurate you can attack), plus the three saving rolls: Fortitude (used to withstand abuse of all kinds - harsh environment, poison, etc...), Reflex (used to evade several kinds of dangers, like explosions or traps) and Willpower (your ability to withstand your urges, or to resist mental effects).

EXAMPLE: Ensign Ricky just isn't lucky today. His Initiative comes up too low, so he goes last in a combat. A surly Klingons tosses a stun grenade his way. Ricky attempts a Reflex save, but fails - he doesn't manage to jump away from the grenade before it goes off. The explosion forces him to make a Fortitude save to resist the stun grenade's effect. Ricky finally catches a break and makes the save. His ears are ringing, but he's still on his feet.

You gain levels in certain classes. This determines how many skill points you get, and grants boni to various derived values. Your class determines to a large degree what kind of archetype your character is...for example, a character with levels in Soldier will be much more combat-focussed than a Snoop. (This does not necessarily mean that he's better at it, but that's a matter of build tweaking.) Classes also grant specific abilities; for the most part, imagine them working like feats. (In fact, some grant specific bonus feats.)

EXAMPLE: Ensign Ricky has had enough of being knocked around in every damn away mission, so he chooses Soldier as his class for the 4th level. While he doesn't get a lot of skill points from it, his derived values - particularly his Fortitude save and base attack bonus - are improved.

The basic challenge mechanic is to take a d20, roll it, then add a bonus (or penalty) depending on your character's stats. This result is then compared to a number call Difficulty Class (DC). If you meet or get over the DC, your roll is a success; if you don't, it's a failure. Again, there's a few details to this, but almost all of the rolls work like that.

EXAMPLE: Ensign Ricky, feeling a bit uppity on his fourth level, tries to phaser a surly Klingon. (Where do they all come from, anyway?) The Klingon has a Defense of 20 - pretty good. Ricky's phaser attack has (all boni considered) a total attack bonus of +7. Ricky rolls a 14 on his d20, then adds his attack bonus for a total of 21. He beats the Klingon's defense - barely. It's pretty much a lucky hit, but hey, who's counting? The phaser beam hits the Klingon in the chest.

That should help you feel not quite as lost in the PDF. If you have questions, ask away.

Gatac