Useful Notes: Role-Playing Game Terms aka: Roleplaying Game Terms
Media complement one another: Movies, TV series, video games, etc. often convert into one another. As they do so, tropes in one genre often become tropes in another. One of these is the Role Playing Game or RPG, a popular form of video games. RPGs themselves are conversions from table-top paper gaming, which often involved acting. (Hence the "Role Playing" part of the name.) As this has increased, we see more and more RPG aspects in series, especially Anime & Manga. See also Role-Playing Game Verse.
RPGs often emphasize numerical statistics. Common characteristics can include:
Stats: numerical ratings that describe your character's parameters in various ways. Your Strength score determines how much you can bench-press, your Intelligence score determines how well you can think, your Charisma score determines how successful you are with the ladies, et cetera. Some games have dozens of Stats for each character, while a few, such as D.U.D.E., have only one. Generally, each Stat is a numeric score on the same scale as every other Stat; if 10 Strength is how strong an average person is, then 10 Intelligence is how smart an average person is. In some game systems, gaining experience points (c.f. below) can increase your Stats. In most systems, Stats will be broken down into Attributes (innate measures of a character's aptitude) and Skills (reflecting training, learning, and study).
Dice: Usually signified by "dX", where X is the number of sides on the die you roll. A traditional die is a d6. Multiple dice are handled by YdX, Y being the number of dice rolled—4d6 means you roll four traditional dice, or one traditional die four times, and add the results. Added to this is the occasional static number, or extra dice—this is usually written out as follows: 4d8 + 2d6 + 3, which means you roll four eight-sided dice, then two six-sided dice, and then add those all up and then add three. Even when there are no actual dice involved, a spell that does 2d12 damage will deal between 2 and 24 damage, tending toward 13.
Character Classes: Your place in the Order of Things is strictly defined, usually in terms of Fighter, Thief, Magic User, Cleric, or Background Character. Along with these roles usually comes standard physical/mental types—fighters are always huge and burly, and not always swift; magic users are always skinny, weak and clumsy while being geniuses; thieves are nimble and clever, and often smaller than other characters. Sometimes subvarieties like Paladin, Barbarian, Illusionist and Druid are available, and sometimes races like Elf and Dwarf will be treated as classes. Clerics will have divine magic (a dead giveaway for a Role-Playing Game Verse). Changing classes is difficult if not impossible. Class systems are clearly visible in Record of Lodoss War and Rune Soldier Louie; in the latter much comedy comes from the fact that Louie is obviously supposed to be a fighter, but he's been raised as a mage.
Hit Points (aka Life Points or HP): How healthy are you? Physical damage can be boiled down to a simple number out of a maximum. Sometimes parts of the body no longer functioning may be included in the loss of HP (such as bones being broken or limbs severed) but often one just glows a bit and grimaces. Full HP or 1 HP is the same in terms of what you can do. Once you get to zero, though...Yu-Gi-Oh! and Code Lyoko have life points.
Magic Points (aka mana, furyoku, chi, Force strength, "power levels" etc. often abbreviated as MP in RPG games ): Spiritual strength can also be quantified. The spirit is like a container of liquid, with "magic" filling it up. The act of casting a spell or equivalent cleanly depletes a percentage of this total. What brings it back up again varies. Examples of this can be seen in Dragon Ball, Shaman King, and Naruto.
Experience: (aka EXP or XP) Curious phenomenon where killing things makes you stronger. It was probably originally supposed to mean that the "experience" of killing the monster (learning from your mistakes, when to duck, physical exertion, etc.) was symbolically represented, however it has evolved to an almost vampiric act. Killing something and absorbing the essence of the opponent builds up the body and mind far more than an equivalent exercise workout. The game-runner can also give out experience for roleplaying and non-combat actions, but as originally conceived...
Character Alignment: Law vs. Chaos. Good vs. Evil. Neutrality in the middle. Possibly a different system, though the Dungeons & Dragons scale referenced here is the one most role-playing gamers will be familiar with. Used as a guide to aid in role-playing specific character types, and sometimes as a straitjacket to prevent you from playing against your character type. Accordingly, some people find it a useful tool, while others find it a pain in the ass. Not present in all Role Playing Games — often rendered as a Karma Meter for simplicity, though almost all D&D-based games will have straight-up alignments included.
Race: Refers more to species than skin color (elves versus hobbits for example). Even subraces (dark elves versus wood elves for example) are distinguished by more than just skin color or nationality. These are popular for giving you another choice, another set of flavor and, most important, another set of bonuses to work with. Though statistical distinction between races is popular from a gaming standpoint, the Unfortunate Implications have occasionally been noted. It also gives the player a chance to play against type (Dwarf wizards and halfling barbarians for example).
Aggro: A multifaceted term used primarily in MMORPGs but slowing seeping into the single-player RPG corner, as well. At the most basic level it refers to the act of an NPC enemy ("mob") attacking a Player Character. If the mob is not programmed to attack on sight or only do so when a PC comes within a certain range, the player can prepare for battle ("before you aggro") and attack, forcing the mob to retaliate ("draw its aggro"). During the battle, a mob can usually only target one of the PCs attacking it, so "aggro" is used in relation to its current target (which can stay the same or change depending on circumstances). Confusingly, the term can also be used interchangeably with "threat" (see below).
Threat: Another MMORPG mechanic that seeps into single-player games. Threat is a (normally) hidden score that the enemy AI assigns to each player character attacking it, so it can prioritize its targets: the higher the score, the higher the likelihood of the AI targeting ("putting the aggro on") that character. Threat score can be raised by a variety of means, including damaging the enemy, assisting your allies who damage the enemy, as well as by special abilities; some special abilities also help lower the threat. "Threat management" refers to players manipulating the threat scores to keep the enemy attacking the Stone Wall characters, while keeping the aggro off Glass Cannons and Combat Medics at all times.
Total Party Kill: When the entire Player Party is wiped out. In tabletop games, it is usually a result of either GMmalice or a series of bad calls on the parts of the players, the GM, or both; the end result is the players having to roll up new characters. In single-player video games, a total party kill is usually the only thing that leads to a Game Over (unless We Cannot Go On Without You is in effect), since individual party members only ever suffer a Non-Lethal K.O.. In multiplayer games, a TPK may kick the players out of an instanced dungeon but rarely has consequences more severe than that.