Basic Mechanic:
Typically actions that your character accomplish take please by rolling a dice pool. Typically that pool will be one d10 for every dot in a certain Attribute and a certain Skill, sometimes with another modifier added in (like the dots of a supernatural power), in rare instances you might roll two Attributes added together, or just one attribute. These pools can potentially have penalties or bonuses placed upon them from the environment, equipment, or from other peoples attributes or qualities resisting against your own.
On your typical roll you need an 8 or higher for the roll to be considered a success, if you roll a 10 you re-roll that dice, potentially gaining yet another success! Sometimes a factor might let you re-roll every 9 and 10 on a dice, and sometimes even every 8, 9, and 10. And other times you might preform a Rote Action which means that you re-roll every failed dice once. If something would reduce your pool to a 0 then you have a Chance Die. A chance die only succeeds on a 10, cannot be re-rolled, and a roll between a 1 - 7 is a dramatic failure.
Types of Actions:
There are three types of actions: Reflexive, Instant, and Extended.
Reflexive Actions: are small things that take little time or energy to preform.
Instant Actions: are actions that take a single turn (3 seconds) unless specified otherwise.
Extended Action: take a variable amount of time, from turns to minutes, to hours, to days, and even weeks. You roll your dice pool and attempt to accumulate successes that the ST sets, you can roll a maximum amount of time equal to how many dice are in the respective pool.
Dramatic Failures:
Dramatic failures occur when you roll between a 1 - 7 on a chance die and in certain rare circumstances. It is exactly as it sounds, dramatic, and never a good way. If you ever roll a normal failure you can turn that failure into a dramatic failure and gain 1 Experience Point and 1 Willpower Point. This can be performed once a scene
Basic Derived Statistics:
Defense: Lower of Wits or Dexterity
Initiative Modifier: Dexterity + Composure
Speed: Species Speed Factor (5 for humans) + Dexterity + Strength
Size: 5 for an adult human
Health: Size + Stamina
Willpower: Resolve + Composure
Willpower:
Willpower is your character's energy and zest for file. A character has permanent Willpower Dots as well as Willpower Points. Willpower points can be spent in ways i'll describe below, and willpower dots are occasionally required for certain rare things within the game. Your willpower cannot exceed your resolve + composure, but if you spend willpower dots you can buy them back with EXP. Your willpower points can never exceed your willpower dots. If your character ever spends all of his willpower points then he is at a -2 to all actions and passive resistances, additionally his Vice, Nature, and any Derangements always come out when he's at 0 Willpower.
You can only spend one willpower point a turn unless specified otherwise, spending a willpower point is a reflexive action. Willpower points are used in the following ways:
To add Three dice to any roll
To add Three to any passive resistance (including defense)
To resist a frenzy for a turn (or more varying on situation)
To activate certain supernatural powers
A single point of willpower can be restored in the following ways:
Acting in accordance with your Vice in a way that hurts or harms yourself and/or another in some emotional or physical way.
Acting in accordance with your Nature.
Accepting a Dramatic Failure on a roll that is a normal failure (see above)
You can gain all of your willpower back if you act in accordance with your Virtue in a way that is self-sacrificing.
Team Actions:
Declaring you are helping someone on an action is an instant action. So long as you have at least one dot in the skill that the parent roll are using you can aid in the roll. When you aid in an action you give the parent roll +1 dice. The amount of times that a roll can be aided depends on what action is being taken, a medicine roll mind only allow two people to aid, while an academic research roll might allow a whole research team. You cannot aid in a combat action. If the action you are aiding is an extended action then you are busy while the extended action goes on.
Vehicles:
Vehicles have statistics. A vehicles handling is added or subtracted from some drive rolls. Here is some example vehicles. If ramming someone with a car you deal 1 lethal for every 10 MPH and you roll the lower of the vehicles size or structure. This counts for car crashes too, its much worse if you don't wear your seat-belt. (wear your seat-belt)
Motorcycle: Durability 2, Size 7, Structure 9, Acceleration 22, Safe Speed 132 (90 miles per hour), Maximum Speed 235 (160 mph), Handling 4-5
Sports Car: Durability 2, Size 9, Structure 12, Acceleration 20, Safe Speed 161 (110 mph), Maximum Speed 235 (160 mph), Handling 4
Compact Car: Durability 3, Size 9, Structure 12, Acceleration 15, Safe Speed 103 (70 mph), Maximum Speed 191 (130 mph), Handling 3
Mid-Sized Car (Sedan): Durability 3, Size 9, Structure 15, Acceleration 14, Safe Speed 110 (75 mph), Maximum Speed 183 (125 mph), Handling 2-3
Full-Sized Car (Family Vehicle): Durability 3, Size 14, Structure 17, Acceleration 12, Safe Speed 103 (70 mph), Maximum Speed 176 (120 mph), Handling 1
SUV/Pick-up Truck: Durability 3, Size 10, Structure 18, Acceleration 13, Safe Speed 103 (70 mph), Maximum Speed 169 (115 mph), Handling 0
18-Wheeler (rig only; no trailer): Durability 3, Size 11, Structure 21, Acceleration 10, Safe Speed 103 (70 mph), Maximum Speed 161 (110 mph), Handling -1
Bus: Durability 3, Size 15, Structure 24, Acceleration 10, Safe Speed 88 (60 mph), Maximum Speed 147 (100 mph), Handling -2
Example Sizes
Size is a category that everyone and everything in nWoD has, here's some examples of sizes 1 - 20