I was on the Geek Gab Game Night podcast just a few moments ago. Nearly two hours on adventure design and other topics – we didn’t hold ourselves tightly to a particular theme. As always, it was a hoot interacting with my gracious hosts, and it definitely plays out as a conversation rather than a lecture!

Give a listen, and of course, support Lost Hall of Tyr!

Last week I sat down with James Introcaso again, and spoke for more than an hour on grappling, Dungeon Grappling, how to publish a game, and how I approach running a Kickstarter, especially as a newbie.

It was a fun interview, and James is a great interlocutor.

Check it out!

TableTop Babble – 040 – 5e Sci Fi and Kickstarter Advice

Reading an article on the differences between Pathfinder and Starfinder.

Well, I guess I was on to something with the Dragon Heresy Wounds/Vigor split.

I’m sure Starfinder has been in development for a long, long time. And I’m also sure I came up with Wounds/Vigor independently, though someone later pointed it out that Wounds and Vitality had long been tucked into an optional rule in the PFRPG Core book.

Still: let me echo that I think it’s absolutely the right call. Differentiating between “stuff that makes you bleed” and “reserve of skill, stamina, luck, and divine favor” as hit points were described on p. 82 of the original Dungeon Masters’ Guide by Gygax is, to me, incredibly useful and helps solve some real problems, especially when you push the game engine into the firearm era.

For now: yay, parallel evolution.

Also: Clearly Starfinder came out first, because, well, Paizo has resources and staff and I’ve got me. But Dragon Heresy, that rough beast, continues to move forward, slouching towards Bethlehem to be born, etc.

 

I was invited by Jasyn Jones and John McGlynn to join them on their Geek Gab podcast to talk about Dungeon Grappling, after I posted my GenCon reports about the playtest.

Well, yeah, we covered grappling. But we also covered GURPS, the DFRPG, game design principles, and many other things, including HEMA and how useful first-hand research can be if you can do it. Roland Warzecha’s Dimicator videos got honorable mention. We talked a lot of 5e, some Pathfinder, a bit of Fate, and WEG’s d6 and GUMSHOE got a nod. I talked quite a bit about Dragon Heresy.

I had a great time, and we spoke for about 75 minutes. I talk kinda fast, but I don’t think I was incoherent, so yay.

Anyway: enjoy!

I’m working through my Grappling Smackdown scenario here, and setting the DCs for various tasks is a thing. I wanted to make a table to quickly inform me of roughly how hard something might be, so I figured I’d share the results. This isn’t a revelation, but it’s useful to me so it might be useful to you.

One useful tidbit from the post on The Standard Array: Joe Human PC with the standard array and who is proficient in a given task will sport a 13.5 attribute as a median, and of course have a +2 proficiency bonus. This makes the average starting boosts to the die rolls about +3.5.

I’ve picked out some example DCs. Obviously moving the DC up or down a point changes the odds of success (on the average) by 5%.

DC 6

At this level, a potted plant that isn’t proficient in the skill has a 50% chance of noticing something or accomplishing a task. I’m having to significantly question why bother rolling at all here. It’s a level that might get interesting if due to unfavorable terrain or darkness or something everyone gets disadvantage.

DC 8

A first level, proficient character with a 10 ability score will still succeed 75% of the time, or a non-proficient character with a 14, a solid but not exceptional DX, for example. This is a good level for a simple task which requires some talent or expertise to get through, but by and large will be a speed bump. Even my potted plant, above (-5 ability score, not proficient) if allowed a roll will succeed on a 13 or higher, 40% of the time.

DC 11

This is still an entry level task, where a completely non-proficient average guy can succeed 50% of the time. The median starting human PC will be succeeding on this by rolling an 8, so 65% chance of success. There’s only a 10% chance of failure for a typical proficient 10th level PC operating in the expert zone. A DC 11 means that it’s still expected most folks will do this well, but the odds of failure for the uninitiated are high.

At DC 11 and DC 12, a non-proficient character rolling against one of their lowest two ability scores (9-11 as a human) will more or less have a 50% chance of success. So it’s the dividing line for “requires some sort of atypical ability or advantage to succeed better than half the time.” Atypical for PCs, that is.

DC 14

Odds of a median first through fourth level PC who is proficient in the skill failing this roll is about 50%. At this level if you’re positing (say) a forked path for adventurers of 1st through 4th level (+2 proficiency), you’re basically saying “flip a coin.” I feel this is a pretty important DC level, as it sets the boundaries for making decisions in adventures. Want your “secret pathway” to come up about half the time? That’s about a DC 14 check . . . but you better be darn sure you have it in your mind that if everyone is allowed a roll, half the median party will fail, and half will succeed, assuming their attributes and skills are spread around a bit.

Anything harder than DC 14 will require advantage, high attributes, and high proficiency to make it a cake-walk. For example, a +4 bonus and +4 proficiency, given as a 10th level character with an 18 or 19 ability score, will still fail this check 25% of the time, although if they have expertise or can eke out advantage from somewhere, they’ll only fail if they crit.

DC 17

Now you’re into telling the GM and PCs you expect them to fail. A first level PC will need to roll 14 or higher to succeed here, and even our hypothetical +8 bonus 10th level proficient character will need to roll 9 or higher (60%). An untrained person using their “dump stat” of (say) 9 or 10 will have a 75-80% failure rate here. Only a true expert (has Expertise in the skill) at high proficiency with an outstanding ability score will be looking at this as trivial.

DC 17, though, is also the level where your low-level party expert (+2 proficiency, +4 in their chosen skill at 4th level due to an ability score improvement) has a 50% chance of success. So much as DC 11 or 12 is the dividing line for making it hard for the unskilled, DC 17 is the line above which only the truly exceptional will succeed more than they fail.

DC 21

Now you’re just being mean. You need +5 proficiency, +5 attribute score, and you have a 50% chance of making this. It’s the break-even for high-level, high-skill “this is still hard” tests. At low level, you’re saying “only a crit will get you here, and only if you have a bonus, at that.” Again, one has to ask why bother unless it’s something that you think the PCs might try but it’ll be pretty silly. Well, yes, you could leap the chasm, but it’s DC 21 . . . chances of success are low.

Parting Shot

So, hopefully this will be of use as a quick reference, if nothing else. Good ability score bonuses to keep in mind are probably +0 (dump stat), +1.5 (median starting character), +3 (expert starting character), and +5 (fully developed unless you’re breaking the 20-maximum rule, as some classes do). Proficiencies are +2 (starting), +4 (mid-level), and +6 (pinnacle). Figure out how likely you want success to be, and adjust from there. Ergo, a handy table. Well, handy for me.

Ability Score Proficiency 25% Success 50% success 75% Success
0 2 18 13 8
0 4 20 15 10
0 6 22 17 12
1.5 2 19.5 14.5 9.5
1.5 4 21.5 16.5 11.5
1.5 6 23.5 18.5 13.5
3 2 21 16 11
3 4 23 18 13
3 6 25 20 15
5 2 23 18 13
5 4 25 20 15
5 6 27 22 17

Wodensday Wonderings is a new feature where I will discuss and comment on things that have sparked my interest of late. Sometimes (like today) it’ll be an animated discussion over mapped vs. mapless combat. Sometimes it might be a game design discussion. Or thoughts about why and why not of firearms and the like in fantasy gaming (to pick on a heated topic I saw on Facebook). More food for thought than “folks should do this,” this is my weekly free association column, so to speak. With that:

I was reading a Google+ post about using mapless/gridless combat, and the poster and commenters were musing about what was basically the tendency of players to precisely place their area effect spells for maximum effect. I’ve seen this too in GURPS games with both spells and grenades.

A quick fix – Random Location

It adds a die roll or three, but there’s an easy way to handle it. Assign scatter to every area effect spell. You can use either d6s or d8s. Continue reading “Spell Targeting – Margin of Error (5e, GURPS, others)”

Setting the Stage

Today Jeffro Johnson linked to a post by The Frisky Pagan where the author analyzes in some depth that Hit Points aren’t really wound points, and why. I pointed out what I call “The Quote,” which is found on p. 82 of the 1st Edition Dungeon Master’s Guide:

“It is quite unreasonable to assume that as a character gains levels of ability in his or her class that a corresponding gain in actual ability to sustain physical damage takes place. It is preposterous to state such an assumption, for if we are to assume that a man is killed by a sword thrust which does 4 hit points of damage, we must similarly assume that a hero could, on the average, withstand five such thrusts before being slain! Why then the increase in hit points? Because these reflect both the actual physical ability of the character to withstand damage – as indicated by constitution bonuses- and a commensurate increase in such areas as skill in combat and similar life-or-death situations, the “sixth sense” which warns the individual of some otherwise unforeseen events, sheer luck, and the fantastic provisions of magical protections and/or divine protection.”

Frisky acknowledged gracefully that reading the original source material is good – in his defense, I think Jeffro has articulated before that no one really knows or can suss out completely all of the gems buried in the barely-edited, scarcely-organized AD&D books.

But that’s not why I’m posting – even though The Frisky Pagan’s post is basically a giant endorsement of the tack I’m taking in Dragon Heresy.

No, the cool bits happened in the comments for Jeffro’s post. Continue reading “Save or Die revisited”

A retroactive (and oft-repeated) introduction: After an actual-play hiatus where I was mostly writing and playtesting for GURPS. I was invited to play in a Pathfinder game, and after a few sessions, it was time to buy the book and learn the rules! I decided to try and read the Pathfinder rules cover-to-cover and see what inspiration strikes, for good or ill!

This is a compilation of the links to read-throughs of Pathfinder-related material

Pathfinder Core Rulebook

0. Prelude
1. Introduction
2. Races

3a. Classes (Barbarian – Monk)
3b. Classes (Paladin – Wizard)

4a. Skills (Appraise – Heal)
4b. Skills (Intimidate – Use Magic Device)

5. Feats

6. Equipment

7. Additional Rules

8a. Combat (Part 1)
8b. Combat (Part 2)

***************

Now we get to the thing that makes the Dungeons and Dragons games somewhat unique, I think – the magic system. Or if not unique (lots of games have magic, and lots do it differently, better, or both), then perhaps it’s that .love it or hate it, the Vancian magic system is a staple of the genre, and Pathfinder builds off of that tradition. This chapter gives the rules for the magic system for those characters who can cast spells. This includes Wizards, Sorcerers, Clerics, Rangers, Paladins, Druids . . . just to start. It’s also possible for some non-casters to pick up some spells too: Rogues can pick up some minor magic, and I’m sure that option exists with the proper Feats allowed.

Casting Spells
Well, first you have to pick one. Knowing it is only enough if you’re one of those classes that can cast any spell they know at any time (subject to the limits on number of spells of a particular type they can cast per day). If you can’t just make stuff up that way, you must memorize, in advance, a number of spells based on your level and class. You can memorize multiple copies of a spell (again, subject to the limits on number of spells at a given level), but for these types of spellcasters, knowing “Wrigley’s Destroying Club” isn’t enough – you must memorize it ahead of time.

Concentration (and Distraction)


To cast a spell, you concentrate on it, subject to distraction. Though the key bit is delayed until rather later, the spell is most often cast right at the instant before your turn comes again – that is, you declare you cast the spell, and right before your turn comes again, your effect occurs. This allows every Tom, Dick, and Hairy to try and disrupt you. 
Distraction can come in many forms, and this section hits all of them. Injury, being grappled, getting slammed with a spell your own self, getting jostled or otherwise shaken-not-stirred, getting tornadoed, or being entangled. You can also “cast defensively,” which means that if you pass a DC 15+2*Spell Level check, you don’t provoke Attacks of Opportunity. Implicit here is that casting spells do provoke such attacks.

Most disruptions simply trigger a check with a DC proportional to the amount of disruption, and each disruption method has its own calculation. Check the handy table on p. 207, or the Pathfinder Reference Document, of course.

Counterspells

You can also use a spell to disrupt another caster. You have to delay your action with a Ready, and when your foe casts a spell, you can make a Spellcraft check at DC 15+your foe’s spell level. If you succeed, you may cast the freakin’ exact same spell being flung at you as a counterspell. Otherwise, you might try Dispel Magic, but that doesn’t always work (some spells can’t be vamoosed by dispel magic, but that’s a spell-by-spell thing). Given how few spell slots you get per day (and maybe if you’re always resting and renewing, this isn’t an problem), I would wonder how often counterspells get used.
Spell Failure

If a spell fails, by and large it just fizzles. No big deal other than the wasted slot and turn. No apparent backfires, dimensional warps, or generally icky consequences. Of course, if you’ve just lost or wasted one of the three memorized spells that makes you a unique special flower, well, that might piss you off a bit.
Special Spell Effects


The key bit here is the (brief) description of what spell bonus types stack and don’t. Dodge bonuses, circumstance bonuses (?), and racial bonuses seem to stack, but most other bonuses and penalties do not, and you only take the worst one. I could see this particular rule being roundly ignored. It’s equal opportunity both ways – since penalties stack as well – and would simplify game play.

Also here is a quick discussion of resurrection, which is the re-merging of the departed soul (literally departed – it goes on vacation on some other plane of existence, and you’re leaving it a voice mail to come back to work) with the body of the fallen. If he doesn’t want to come back, he doesn’t have to. And if enemies want to keep him away, there are ways of either trapping or warding the soul . . . or you can just filch the body, since you need it for the spell!

Multiple Spell Effects


This entire section made me want to dig out my +3 Red Pen of Editing, and write “stop being so wishy-washy” over and over. This little section is in rather desperate need of a few examples. Generally, if you’re providing different types of effects (like a DEX buff and a STR buff, or Enlarge Person and a CON boost or something) things probably go to plan. You can’t give multiple stacking spells of the same type: Two +1 boosts to STR are just +1, and a +1 and a +2 only gives you the benefit of the larger one. Finally, if you cast a series of spells with similar effects, usually it’s the most recent one that applies.

It also throws you under the bus with nice vague advice like “sometimes a spell can make another spell irrelevant!” Gee, thanks. This section is basically some vague GM guidelines, and there aren’t many nuggets here.

Spell Descriptions


At over 100 pages, Chapter 10 is the largest chapter in the book, and it’s “nothing” but spell after spell. So in Chapter 9, we break down the content of the spell descriptions, and what they mean.

School of Magic


Most belong to one of eight schools.

  • Abjuration: protection spells. Some such spells, especially if multiple spells are laid on top of each other, are detectable by Perception.
  • Conjuration: Movement and alteration of living creatures and some objects, I think. There are subschools which are pretty descriptive. Calling spells brings a critter to you from another plane. Creation forms magical constructs that disappear when the spell is over. Healing conjurations make you all better. Summoning brings a pre-existing creature or object to you, which goes back to where you sent it when killed or dismissed. Finally, Teleportation spells are when you’ve got to move it move it, and instantly transport things from place to place.
  • Divination: See secrets, know the future (the GM’s bane), find hidden things. 
  • Enchantment: Mind-affecting spells that change how the subject views you (charms), or force behavior (compulsions).
  • Evocation: boom sticks. Creating and manipulating magical energy, often in highly visible ways to cause damage.
  • Illusion: deceiving the senses of others. There are several kinds of illusions, such as figments (false sensations), glamers (glamour? altering how something looks, tastes, feels, etc.), and others. You’ll generally treat an illusion as real unless you take the time to interact with it, whereupon careful study might reveal and dispel it – that’s a saving throw.
  • Necromancy: Dead things, Mikey. Dead things. The undead, manipulating the forces of life and death.
  • Transmutation: Changing the properties of a thing or person from one form to another. This can inlcude polymorph to change your own body or that of another. There’s a very large block of text here on polymorph, so if that’s going to be your thing, you’d best read it.
Descriptors
Mostly these are fluff text that carry no game-mechanical interaction about the spell itself, but it does say that they can give interaction info on how it plays with other spells. 
Components

Spell components can be a big deal. You can’t cast a spell if you can’t fulfill the requirements! Verbal components require that you be able to speak clearly, as if on stage or giving a lecture. Somatic components are hand gestures (I had always thought they could be full-body movements. Guess not!). Material components are consumed in the casting, but the game says don’t bother to track them unless they carry a cost. Interesting. Focus is new to me, but it’s basically a non-consumed prop that helps cast the spell. Divine Focus is basically a holy something. It might be a sprig of a holy plant for druids and rangers, a holy symbol or reliquary for a cleric.
Casting Time

As mentioned earlier, some spells can be cast in a standard or swift action (which presumably mean they take effect right as you cast them), others are full-round actions (they go zap right before you take your next turn), others can take minutes, which means you get to take ten combat rounds to do this. Better have efficient friends. Or cast out of combat. You only make decisions about range,target, area effect when the spell takes effect, not at casting.
Range

Provides some pretty concise definitions and advice on ranged spells. Personal (you only), touch (up to six people using a full-round action might be allowed by some spells), then Close, Medium, Long, and Unlimited. Except when range is just expressed in feet. Most ranges seem to extend a bit with caster level (+5, +10, +40 feet per two full caster levels).
This section goes on for a bit, talking about rays, cones, spreading fogs, etc. It gives templates for various lines, cones, and radius effects, but the entire section is worth noting. 
Oops. Failed Saving Throw.

Duration


Most of the duration rules are straight-forward. One cool bit is that touch spells can be held for the entire duration of the spell, which means if you can cast some nasty fire-hand spell for a minute, you can set people’s face on fire for ten rounds. Not too shabby.
Saving Throws

Some spells can have their effects reduced or even eliminated with a saving throw (some spells are no-save allowed, though). The DC is 10+Spell Level+any applicable bonuses, which for dedicated spellcasters are going to be in the +3 to +5 range. So probably DC 15 and higher, by and large.
Spell Resistance

Basically AC for spells. You have to overcome this if your target has it – 1d20+Caster Level vs. your foe’s Spell Resistance, 
Arcane Spells

I will have to admit that at this point, my brain just started shouting out “my God, the tedium!” I know that these rules are core to a caster’s mission in life. How they prepare spells, what the limits are to casting, how they’re recorded in the spellbook, etc.

But the writing is terribly terribly dull. For a book filled with iconic characters, I really wish they’d have used them more to provide flavor and examples.

Still:

Preparing Spells


You must rest for 8 hours, and then take 15 – 60 minutes to prepare your slots. Somewhere buried in there (Prepared Spell Retention) it gives what is a pretty good explanation for this “memorization” thing. You are actually effectively partially casting, and then “hanging” the spell, subject to finalization and execution later.

I should note that the new(ish) GURPS magic system introduced in Monster Hunters – Ritual Path Magic – has something very, very like this. You take the time and energy to cast a spell into a focus, called a charm or dweomer, and then when it’s time to cast the spell, you crush or otherwise activate the item. Spells can take a long time to prepare, and the ability to generate a monster (ahem) spell repertoire is limited to your magic power and really how much time your friends will let you spend muttering incantations before you head out to kill stuff.

If you’re playing a wizard or sorcerer – or any spellcaster, since the rules for Divine spellcasting are best summarized as ‘exactly the same thing, with this small handful of changes – you will want to read these rules a few times, and discuss them with your GM to see if he has any house rules to (hopefully) smooth things along in game.

Short version though. You rest for the night (8 hours), you spend about an hour to prepare stuff. If you’re disrupted in your rest you either need to make it up or prepare fewer spells. It seems to take roughly 60-90 seconds per spell regardless of level (about an hour, maximum of 40-60 spells total memorized, ish).

You can leave spell slots open and prepare them later. If you are facing a journey where you can make frequent stops of about an hour, this might be the best way to ensure you don’t leave yourself utterly without the ability to be flexible. It still takes at least 15 minutes to get this done, and you may not abandon a previously memorized spell in this process. You may only fill an empty slot.

Spellbooks



The rules put a lot of thought into the wizard’s spellbook, which is exactly 100 pages, no more, no less. Each spell, from zero-level to 9th level, is one page. Magical writing is a sort of personal arcane shorthand that has as much to do with how your character interprets magic as with any sort of formalism. Thus, it takes a bit to unravel another wizard’s shorthand, which is why it takes so darn long to read them.

It’s a neat trick – DC 20 + the spell level.

You can also prepare a spell from another person’s book, but you have to make a Spellcraft check (DC 15+level) to do it. Copying a spell is a similar check, but it costs a bunch of money: square the spell’s level x 10 gp (5 gp flat cost for 0-level spells). You must be writing in solid gold ink or something – or the ink itself is magical. Still, as they say in my neck of the woods, that’s ‘spendy.’

You can sell a spellbook as loot for half the gp cost of all the spells it contains. The spellbook of a powerful caster that might have 4 spells per level x all 10 possible levels of spells is worth about 5700gp. Not bad as treasure.

Divine Spells

Pretty much just like Arcane spells, but you prepare them at a time of your choosing instead of right when you wake up. Also, any spell slot of appropriate level or higher can be used to cast a healing (or inflict harm) type spell, so you don’t need to prepare those in advance, per se, but you will need to decide what you need to give up as you go. This also works for summon nature’s ally if you’re a druid.

Special Abilities

Some abilities mimic that of spells in certain ways.
Spell-like Abilities are not exactly spells, but duplicate the function of a spell and are definitely magical in nature. You can just ‘turn them on’ with a standard action with no verbal, somatic, material, or focus requirement, and they do not provoke Attacks of Opportunity. However, they can be dispelled and don’t work in areas that disallow magic. 
Supernatural Abilities cannot be disrupted in combat – so they’re wicked cool – and thus aren’t subject to spell resistance or dispel magic, but they don’t function in antimagic areas.
Extraordinary Abilities may look like spells and feel like spells, but they’re not. They’re not magical, can’t be dispelled, don’t suffer the effects of antimagic or dispel magic . . . basically they break the laws of physics for reasons that are not magical or anything. 
Parting Shot


While this chapter is critical to understanding and playing spell-users in Pathfinder, it’s quite a slog to get through. Still, while there are many rules, there seem to be relatively few special cases, so once you assimilate the laws of magic, so to speak, you should be good to go for the rest of your Pathfinder career – unless other books that aren’t the Core Rulebook change that!

A retroactive (and oft-repeated) introduction: After an actual-play hiatus where I was mostly writing and playtesting for GURPS. I was invited to play in a Pathfinder game, and after a few sessions, it was time to buy the book and learn the rules! I decided to try and read the Pathfinder rules cover-to-cover and see what inspiration strikes, for good or ill!

This is a compilation of the links to read-throughs of Pathfinder-related material


Pathfinder Core Rulebook

0.  Prelude
1.  Introduction
2.  Races


3a. Classes (Barbarian – Monk)
3b. Classes (Paladin – Wizard)

******

When last we left our heroes, we were just finishing up the section on recovering from wounds in the Combat chapter, with some snarky notes on so-called “non-lethal” damage. Ah, well, Pathfinder isn’t the only game to make that mistake, and so we continue.

Movement, Position, and Distance

The game first drops something that’s not really a surprise, but is one of those “oh, OK, then” moments. It basically requires, or at least strongly encourages, miniatures and a mapboard to play, and even gives you the desired scale of the minis: 30mm.
In any event, the game is resolved on a square grid with 5′ squares, and you basically take your move, modify it for your size and any special encumbrance you have, and divide by 5′, and you get that many squares. For most PCs, that number is likely six.
Diagonal movement counts 3 squares for every 2 squares traversed, but it’s broken up as your first diagonal only costs 1 square, but your second – no matter where in the sequence it comes – counts as 2 squares. So net/net, you pay the right amount. Don’t do the “1-2-1-2-1” thing through difficult terrain, though – if you’re doing that, move costs are doubled, so each diagonal costs you the full 3 squares, rather than something staggered.
Moving Through a Square

Now we get into special case land. It’s probably wise to note down the things your character will expect to do a lot, and jot down the rules. You can always move through a friend, unless you’re charging. You can’t move through a foe, unless he’s helpless. Or big. You can’t put two critters in one 5′ square, again unless he’s helpless. If you’re trying an “overrun,” you can try and move through hs hex, but it might backfire on you. You can move through a foe’s hex if you’re using acrobatics, or you’re fine, diminutive, or tiny. 
Got that? Oh, well, sometimes it’s wrong, but exceptions will be noted.
Critter Size

While big guys are easy (they fill their squares, so stay out), you can jam 4 Tiny guys, 25 Diminutives, or 100 Fine nasties in one 5′ square, and by and large they can’t reach into adjacent squared to attack, so they have to enter your hex, provoke an attack of opportunity, live through it, and then crawl up your pant leg.
The only other thing to note about large guys is that using natural attacks, instead of weapons, they threaten not just the ring of squares 10′ away, but the adjacent squares as well. Take note, be warned, etc. You’re not safe one square away from these guys.
Combat Modifiers

The game differentiates mechanically between cover and concealment, which should please my infantryman friends. However, the flat distribution of die rolls makes this interesting. Wait and see.
For Cover, you basically pick a corner of your own square (naturally the most advantageous one), and if the line from that corner to any corner of your foe’s occupied squares passes through a wall or other hard obstacle, then your foe has some sort of cover.
If the entire foe is occluded, you can’t attack him at all. If up to 50% is covered (partial cover), your foe gets +2 to his AC, and if from 50-99% is covered, he gets +4. There are some picky rules about half-height obstacles, and covered foes can get bonuses to Reflex saves (+2) under some circumstances. There’s also improved cover which can give +8 to your foe’s AC, but that’s GM discretion for things like arrow slits.
Note that what full cover does, effectively, is make your foe 20% more difficult to hit. 
For Concealment, you’re more or less using the same resolution mechanics, but when you’re done, a concealed foe rolls d% and you miss 20% of the time, or 50% of the time if you’re shooting into a totally concealed square that contains your foe but you can’t see him.
That’s not quite the same as “you’re 20% more difficult to hit,” since that AC adjustment can take you from (say) hitting 50% of the time to hitting 30% of the time. With the “you miss 20% of your hits,” you’d go from hitting 50% of the time to hitting (50% hit rate x [1-20% miss rate] = ) 40% of the time.  If you were hitting 80% of the time, you’d be down to 64%, but if you only had a 20% chance to hit to begin with (say, 1d20 vs AC 17) then rather than it being basically impossible for you to hit (1d20 vs AC 21) you could still roll a potential hit 20% of the time, but 20% of those hits would convert to misses – a 12% net chance of success.
So concealment is similar in resolution but less harsh mechanically.
Flanking

In melee combat, if you and a friend are threatening the other guy from opposite sides, you’re flanking him, and you get +2 to hit. Pretty sure that if you and a buddy are flanking a foe, you get to apply your Sneak Attack damage, so ths one’s pretty key. 
Note that just being “behind” someone doesn’t seem to qualify (at least, not at this point in the rules). You need to be splitting his attention between two people.
Special Attacks
The last sprint to the finish contains a bunch of special attack types, including Aid Another, Charge, Combat Maneuvers, Feint, Mounted Combat, Throw Splash Weapon, and Two-Weapon Fighting.

Aid Another: You and your buds can make attacks vs AC 10, and each one that succeeds can give a designated friend either +2 to his hit roll or +2 to his AC, and those adds stack. 
Charge: Near as I can tell, using a full action you can travel up to 2x your normal move, but only in a straight line unhindered by any obstacles or difficult terrain. You need to end in attack range, whereupon you get +2 to your hit roll and -2 to your AC. You may only attack once. If you’re using a lance (pay attention, knight wannabees) while mounted, you do double damage by default. If you’re charging a group of guys with braced weapons, you’re going to be on the receiving end of said double damage.
Feint:  As +Fred Brackin pointed out many moons ago, this important special attack, if successul, denies your foe his DEX bonus on the subsequent turn. Since lots of nifty Rogue and certain Archer abilities are keyed to “your foe loses his DEX bonus,” this is a great way to benefit from things like Sneak Attack without having to flank or stealth your way into place. It’s Bluff on your end, vs. 10+BAB+Wisdom modifier, or 10+Sense Motive bonus if it’s higher.
Mounted Combat: Mounts have some nice features. They act on your Initiative, and when they move (and ergo, you go along for the ride), they use up their own move action, not yours. That being said, you only ever get one attack while mounted if you also move, but you may still charge, and if you’re striking down at a foe, you get a +1. You can still hack away with multiple attacks if you only take your five-foot step, though.
Throw Splash Weapon: The Alchemist’s favorite. You can toss something that does a bunch of nastiness and it will do direct damage to whomever it hits as a ranged touch attack and splashes everyone within five feet of that individual. You may also target the vertex of a square at only AC 5. You lose your chance to do direct damage, but hey, AC 5, and you splash the four squares attached to that vertex. Your GM will afterwards keep proper separation between his NPCs; or the PCs will do likewise if they’re on the receiving end of this. 
Two-Weapon Fighting: The Ranger’s fave, basically anyone can do this, but the penalties can suck. If you have a light weapon in your off hand, it gets better, if you have the Two-Weapon Fighting feat, it’s better still, and if you combine ’em, you can attack twice at only -2 each. Since that’s only a 10% loss to success chances, unless your chances of hitting are worse than 25%, you will want to use two weapons if you are only -2 to hit. If you only have Two-Weapon fighting, you are at -4 to each attack, and so you make one attack if your chance of success on a single attack is worse than 50%. Your odds of missing with both double-weapon attacks are larger than your odds of missing with your single shot. On the high end, swing twice, always. Untrained, it’s never better to use two weapons without the feat unless you effectively can’t fail. That’s not a sophisticated damage per attack round analysis, though, just a “don’t miss” one. Properly, you’d take the weighted average damage of one hit vs. the weighted average (at reduced hit chance) of two, which can have two hits, one hit, or none. Not in the mood tonight.

In the comments section, +Fred Brackin does a pretty good job of demolishing Two-Weapon Fighting as a good plan. While the straight-up to-hit odds sorta favor you in the first analysis as above, he does a better calculation vs a typical armor class in terms of damage over ten rounds. He also makes the point of what you give up to get this two-weapon ability by selecting a feat, as well as the AC bonus from a shield. Plus, two-handed weapons like greatswords kinda rock. Scroll down and read the whole thing, and you might come to the conclusion that two-weapon fighting is a waste of time!

Combat Manuevers

This deserves its own section. You can do one of these using your Combat Maneuver Bonus, equal to your BAB+STR modifier+any special size modifier, and bigger is better. On the Defense, your target number benefits from both STR and DEX, and once again size helps.
What can you do?
Bull Rush: As part of a standard action or charge, you can try and push a foe straight back without doing any harm. This is football. You can theoretically even bull rush two or more foes, if you can absorb the -4 penalty per critter, but you get a new roll each time.
Disarm: Doing this provokes an attack of opportunity. But the value is obvious if you can pull it off. If you win, he drops one item of your choice; win by 10, and both hands are empty. Fail by 10 or more, and you disarm yourself. Oops. If you managed to do this while unarmed yourself, you can take the weapon from him and keep it, automatically. 
Grapple: Provokes an Attack of Opportunity. If you win, you change his state to grappled. He can’t move, is -4 to DEX, and -2 to all attacks that don’t involve breaking the grapple. See p. 567. Actually, don’t. See here instead (this online rules stuff is kinda cool at times). From grappled, you can also Move him, damage him with an unarmed attack, pin him, or even tie him up. Go go gadget bondage!
Overrun: This is one way to move through a foe’s hex without his permission. He can get out of the way, which lets you pass. If you win the maneuver check, you go through, win by 5 or more, you knock him prone.

Sunder: Break his stuff! Make an attack on his weapon, and you can damage or destroy it.
Trip: An attempt to knock your foe prone from up close, as opposed to an accidental/extra-good result of an Overrun. 
Special Initiative Actions

There are a few things you can also do with turn order.
Delay: This voluntarily sets your initiative to a lower number than what you rolled for the rest of the combat. You can do this multiple times, reducing (but never raising) your Initiative number.
Ready: Prepare to take a specified action at some time between your initiative count and your next turn. This one also resets your initiative count, but only (I think) if you actually interrupt another character with your action. So you have Init 17, and you’re waiting for that spellcaster to poke his face out of cover on Init 8 to shoot him with an arrow. He pokes out on his turn, and you shot him in the face. Your Initiative is now effectively 8.1 – you go right before the wizard, for the rest of the combat.
You can attack spellcasters to distract them, you can ready counterspells, and you can also ready weapons against a charge – and you go first, assuming your reach is longer than his . . . 
Parting Shot
And that’s the combat chapter! I’ve already learned some new things, so it was definitely worthwhile. Still a lot of special cases, which you can and should avoid by Being a Better Player. A bit of pre-prep in a game as rules-exception heavy as this one can go a long way.