People who are not from the “gamer generation” – those who are above 30 years old, according to the definition by Michael and Beck (2005) – often ask me what is this “mod” / “modding” I am talking about.
The short answer is that the word “mod” originates from “modify.” Hence, a gamer who has modified part of a computer game with something s/he created, the person is referred to as a “modder” and the game artifact created, a game mod (or “mod,” for short). Modding, is of course the present continuous tense for the verb, mod. (Why not simply use the word, “modify”?) It is SO ordinary and not befitting the cool image of a modder, who is necessarily some geek if s/he is to be able to pull off modding.)
Well, here’s another perspective from wikipedia’s entry on Mod (computer gaming):
Mod or modification is a term generally applied to computer games, especially first-person shooters (FPS) and real-time strategy (RTS) games.Mods are made by the general public, and can be entirely new games in themselves. They can include new items, weapons, characters, enemies, models, modes, textures, levels, story lines and game modes. They also usually take place in unique locations. They can be single-player or multiplayers. (Some mods merely contain new contents, whereas some mods are entirely new games.) These mods can add extra replay value and interest.
Mods can significantly outshine or continue the success of the original game. Playing a mod might even become more common than playing the unmodified original. In those cases, players might have to clarify that they are referring to the unmodified game when talking about playing a game. In some cases the term vanilla (or the prefix ‘v’, or ‘V’) is used to denote the original, unmodified game, e.g. “vanilla Battlefield 1942″, and “vanilla Quake 3″ (or VQ3).
The Internet provides an inexpensive medium to promote and distribute mods, and they have become an increasingly important factor in the commercial success of some games. Developers such as id Software, Valve Software, Bethesda Softworks, and Epic Games provide extensive tools and documentation to assist mod makers, leveraging the potential success brought in by a popular mod.
Examples include: id Software (mods of Doom & Quake), Valve Software (Counter Strke - a complete mod created using Half-Life’s Source engine), Bethesda Software (The Elder Scrolls [TES] Construction Set), Epic Games (mods of Unreal).
So there you have it.
So far, majority of the game development kit (GDK) given away by game publishers only work on PCs. (Meaning, if you are interested in doing modding research, stick with a windows machine. Mac and Linux are seldom supported.)