killer app – A piece of software (such as a game) which is highly popular and successful. Starcraft in Korea.
Kojima, Hideo – Currently working on his fourth last Metal Gear game.
lag – The time delay between sending and receiving online data. A popular excuse for suckage, and a popular feature of the Wii’s wi-fi support.
LAN party – A gathering of gamers who bring their PCs and set up a local area network to play multiplayer games. Also known as a sausage-fest.
LFG – “Looking for group,” the desperate cry of a lonely MMOG player.
localization – Any modifications (such as translation) made to a game in order to market it to a culture outside of the one it was originally developed for. Responsible for such gems as "All your base are belong to us."
lolercoaster – Worth the price of admission.
machinima - Never funny (Full Life Consequences not included).
mainstream media - Non-specialist publications which generally love Nintendo (the Wii is revolutionary!), think gamers are socially inept (unless they own a Wii!), and are subjected to more hate than even the worst forum trolls.
Miyamoto, Shigeru - The godfather of videogames. Has since lost his mind.
motion blur - When you just don’t feel like rendering anything.
MMO - Massively Multiplayer Online… what? Online what?
MMOG - Massively Multiplayer Online Game.
MMORPG - World of Warcraft, and the rest.
Molyneux, Peter - Designer of painstakingly complex dog AIs.
nerf - To f**k up.
next-gen - Oddly refers to the current generation of consoles.