Terminology

Any terms used only in (or originate from) video games or video gaming that are not self-explanatory. Not for game genre names, nor terms specific to a game.

# A #
Add : Enemy found with or summoned by a bigger enemy (such as a `Boss´). Generally the minion(s) of another.
Aggro : An (NPC) enemy that attacks player characters simply by spotting them or being too close to them (as in, it's aggressive). Usually heard in MMOs only, where some/most enemies happily wait for players to initiate fights.
AoE : see `Area of Effect´
AoE [character type] : a character that specializes in fighting multiple enemies simultaneously. Commonly magic users (AoE casters) but can be anything.
Area of Effect (AoE) : anything that applies to a large area, such as a grenade has AoE blast damage due to the explosion.
# B #
Boss : an extremely powerful being that often is found at the end of a level or at a significant plot point, commonly unique within the playthrough.
Buff : an effect that boosts certain traits of a character, commonly temporarily.
# C #
Camper : a player who sits long periods in a single (usually well protected, hidden, or well out of range of most weapons) spot where they have good view of all or most possible places opponents may appear from whence they engage them. The behaviour is similar to how real-life snipers work, though in games this can include even people using melee attacks. Generally seen as abusing some poorly balanced aspect of a game, regardless if this is true. Has also come to refer to players who just sit in defensive positions but contribute little to completing objectives that need to be completed to win the games as well.
Camping : see `camper´
Cloaking : ability to become (almost) completely undetectable.
CD : see `cooldown´
Character level : a generic measure of character's power, efficiency, or usefulness.
Cooldown : a generally artificial delay in re-using an ability, spell, skill, or such.
Creep : see `non-player character´
# D #
Damage over Time (DoT) : damage that is applied over a span of time rather than instantaneously, commonly poison, bleeding, burning, or similar.
Damage per Second (DPS) : how fast something or someone deals damage over time, generally seen as function of attack damage divided by attack speed. A DPS is a character or item with high damage per second
DoT : see `Damage over Time´
DPS : see `Damage per Second´
Drop : loot "dropped" by NPCs, likely refers to old games (though still present in many modern games) where any items the NPCs might've had drop near them when they are defeated rather than requiring scavenging through their bodies.
Dungeon : a location infested with monsters, outlaws, evildoers or some other beings you don't think should stay alive for much longer. This can be a hideout, a stronghold, a forest, a cave, a house, etc.
# E #
Eq : short for equipment
Experience : generally a counter for reaching a new `character level´
# F #
Farming : defeating large numbers of AI controlled opponents to collect their loot, either for acquiring wealth, ingredients, or some rare loot.
Fog of War : although in military terms this refers to general uncertainty in situational awareness, in games this refers to a literal shroud of darkness that impedes perception significantly, sometimes used to simulate limitations of sight in top-down games by making it very clear what areas the units can or can't see by distance.
# G #
Gib : a meaty, bony, and/or bloody chunk of a former character or other creature; the act of killing an opponent that produces them (may involve explosives or overkill).
Griefer : a player in a multiplayer game who irritates and/or harasses other players intentionally.
Grinding : any kind of repetitive play done by the player, often referred to in derogatory manner though includes even instances that are entertaining to the players.
# H #
Hit points (HP) : a pool representing the general well being of an entity. Also called health points. Term likely originates from games where any kind of damage would only drain one point from the pool regardless what it was, thus counting how many hits you can take before dying rather than how much beating you can actually take (in terms of realism).
HP : see `hit points´; also short for health points.
# I #
# J #
# K #
Kill steal : Games generally reward a kill to the person who deals the final blow to a being, so kill steal would be letting someone else do the hard work of withering down someone or something to low health and then jumping in on the chance to last hit and therefore being registered as the one who killed the thing and gaining the rewards without actually doing the hard work. Some games include safeguards against this.
KS : see `kill steal´
Kite : see `kiting´
Kiting : running away from an opponent while shooting at them (constantly or occasionally) while staying outside of their range. Looks like flying a kite except the "kite" is the enemy. Usually seen with ranged character kiting a melee character.
# L #
Level : a location or a `character level´
Level of Detail : (tech) any algorithm that decides on how complex/detailed objects, textures, etc. should be drawn at a given distance. Often not configurable by player, but may have bias options available.
Line of Sight : A direct line drawn from one's eyes to the target, usually to indicate that certain objects block this and thus anything within Line of Sight is what isn't blocked. Also in terms of certain actions where it is used to denote that it can not be used on things unseen.
LoD : see `Level of Detail´
Loot : anything useful found from scavenging, pillaging, stealing or dropped by mobs.
LoS : see `Line of Sight´
# M #
Map : a location, not the tool for locating things
Mob : short for `mobile´, see `non-player character´; term originates from MUDs and used regardless if the entity was actually moving or not.
Monster : when not used in literal sense, refers to any `non-player character´ regardless if they're actually monsters (e.g. a bandit could be a `monster´).
Magic points (MP) : a generic pool of "points" that can be expended for casting magical spells, using abilities, or other things. Can be viewed as a type of energy pool.
MP : see `magic points´; alternatively magic power
# N #
Newb : see `newbie´, commonly used derogatorily
Newbie : a new player or player who is new to a character or game, or a player who doesn't know how to play (well) yet. Slightly different meaning compared to the term used in life.
Nerf : the act of game developers reducing the effectiveness or usefulness of something, commonly happens in patches, especially for `PvP´ multiplayer games.
Non-player character (NPC) : any non-human controlled character, being, vehicle, or other similar entity within a game.
Noob : see `newbie´, commonly used derogatorily
NPC : see `non-player character´
Nuke : a character or ability that does excessive amounts of damage compared to anything else. Commonly a magic user. Can be literal nuclear weapon occasionally.
Nuker : specifically a `nuke´ character
# O #
OP : overpowered; see also `unbalanced´
# P #
PBEM : acronym for `play by e-mail´, an online multiplayer option often found in turn-based games.
Party : a group, squad, or other informal collection of people working together.
PuG : Pickup group, a group person is placed in usually due to matchmaking or similar automated process. Often viewed derogatorily.
Pulling : attracting singular targets or small groups out of larger mass of enemies, usually for the purpose of avoiding fighting too many enemies at the same time or avoiding tougher opponents while still fighting some of the available opponents. Implies some/all of the enemies are aggro. Sometimes more clearly called "luring".
PvP : player versus player
# Q #
Quest : a job, mission, task, or some other deed someone has requested you to accomplish, regardless if this involves payment or anything else. Note that although quest can refer to such a thing in certain circumstances in reality, in games `quest´ tends to be used for all cases, such as fetching eggs from chicken coop can be a quest.
# R #
Raid : either `raid boss´ or `raid party´.
Raid boss : a `boss´ that requires a `raid party´ to defeat
Raid party : multiple parties (see `party´) joined together for a `raid boss´
# S #
Save scumming : excessive save game reloading (and thus saving) to get favourable/optimal results OR a practice of circumventing a game's permanent death mechanic by backing up one's saves so they can be restored afterwards.
Skillshot : usually an ability, spell, etc. that has travel time and hitting something is not guaranteed thus requires skill to hit by leading a target or otherwise getting the target in the path of the "skillshot".
SP : see `magic points´
Spell points (SP) : see `magic points´; alternatively spell power
# T #
Tanking : functioning as a `tank´
Tank : a character that can take a lot of damage without dying or becoming incapacitated, commonly these protect weaker members of a group.
# U #
UB : see `unbalanced´; see also `OP´
Unbalanced : a feature that has not seen sufficient playtesting and is subject to being nerfed (see `nerf´) due to it being too useful that everyone gets or uses it if possible, often ignoring many other features in the process that are supposed to be of equal usefulness. Seen only in multiplayer games.
# V #
Void : the space outside of most playable areas (mostly in 3D games), commonly so undefined that this causes graphical glitching, x-ray vision to many locations, as well as subjecting the player character to gravity without having anything or anywhere to fall on (falling endlessly with the level receding from sight above). Commonly reached via game bugs or cheats (e.g. no-clip).
# W #
WEGO : referring to turn-based games where the norm is alternating turns (I go, You go) and turn it into simultaneous (We go).
# X #
XP : see `experience´
# Y #
# Z #

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Any addition, clarification, etc. requests can be sent to me via PM or as a reply to this thread. Editors may directly edit this article.

Fog of War ?
HP ?
Camping / Camper ?

Maybe Creep / Creeps but I don't know if it's Warcraft III-specific or used for other games now.

All tower defense and MOBA games (that I've tried) call NPCs creeps, so they belong to the mob/mobile/monster/NPC category.

Line of Sight
Level of Detail (the acronym, LOD, applies to at least 12 game related concepts)

Line of sight is not gaming specific and thus should't be included. Don't know any meanings for it that deviate from the non-game related concept like with map and level.

Level of Detail is technical concept not actually used for talking about gameplay or anything such, so I'm not sure there's use including it. Any mention of LoD actually appears rarely nowadays due to any options related to it being removed and when they are, they're very straightforward (the amount of detail, unrelated to LoD algorithms).

Edit #: Wikipedia would seem to disagree with me on this, but what it describes is what dictionary says on line of sight. In games it's just indicator that line of sight is actually simulated, not a game concept that is added. It's like explaining jumping here.

And videogame collector's terms. To compliment the above list whilst being separate from it.

#M#
Mint : Mint condition. A reference to the perfect physical condition of game media, packaging, and included materials.
MIB : Mint in box. Implies that game package has been opened but everything is still in mint condition.
#N#
NIB : New in box. Indicates the game has never been sold to a customer who played it. Strongly implies it has never left the possession of a retailer after it's initial shipping. Condition of the package is a separate concern.
#S#
Shrinkwrapped : A reference plastic wrapping around a game packaging having never been removed.

Those are as far as I know general collector/trading terms applicable to anything and thus not really video game specific terminology (probably should clarify that in the initial post).

Edit: Little better clarification in initial post, probably not sufficient tho.

I seem to have went against my own statement and added non-video game specific terms in there, and now looking at it there doesn't seem to be neat way to separate them, so I'll just add the things you (Zerothis) suggested.