Have you ever wanted to make changes to a game while you were playing it? Perhaps you thought your weapons were too weak, or you were frustrated by your incompetent AI teammates. Maybe you simply weren't satisfied with something more fundamental. Well, you're not alone -- there are hundreds of thousands of players out there who like to make modifications ("mods") to the games they own, ranging from humble subtle changes and bug fixes to complete overhauls that leave very little of the original game intact.
Modding isn't just fun and games, though! The skills you learn while making a game mod can be the beginning of your career in game development. In this article, we're going to walk you through the basic information about modding games; we'll discuss modding history, popular games and engines, and a few stories of modders-turned-developers -- to encourage you to start making your own.
If you're interested in making your own games, building a few mods is a great way to get your feet wet. When you're trying to make a game from scratch, it's easy to get stalled early on-especially if you're working by yourself and don't have the skills or time to do all the art, sound, coding, designing, and testing all by yourself. On the other hand, if you decide to modify an existing game, you already have an excellent base to start from, and you get to jump straight to the game-making process.
Also, modding can also be a good way to start building your portfolio for when you're ready to start looking for work as a game developer, since you can start practicing your level design, 2D and 3D art skills, sound design, and other game development disciplines without having to make a game from scratch first.
A Brief History of Mods
Game mods have been around for nearly as long as games themselves have; Steve Russell's Spacewar! (1962) had plenty of third-party additions, including cloaking generators, different weapons, and even a first-person perspective. Ms. Pac-Man started out as a thirdparty Pac-Man conversion kit called Crazy Otto. And one of the earliest games to feature aftermarket mod support was actually Microso ft Flight Simulator 4.0's Aircraft and Scenery Designer expansion pack (1990).
Most of modern modding activity can trace itself back to id Software's Wolfenstein 3D release in 1992; its codebase was particularly easy for enthusiasts to play with, so many people made new level packs that extended the life of the game. Id noticed this and built Doom with deliberate flexibility in mind by separating the code, media, and levels into modular .wad packages to make it easier for modders to distribute their changes, and would continue to encourage modders to work with the Quake series by including modding tools and eventually making their engines open-source.
Since then, we've seen many major games grow from humble game-mod origins into full-fledged triple-A titles-or in some cases, entirely new genres. Counter-Strike, one of the most legendary online games in history and the forefather of practically every realistic FPS out there, started out as a Half-Life mod. League of Legends, Heroes of Newerth, and other games in the emerging multiplayer online battleground (MOBA) genre all share one common ancestor: Warcraft III mod Defense of the Ancients. If you have a great idea for a mod, you might find that it can eclipse the original game you modified!
The Big Three
Unreal Engine (Epic Games)
The Unreal Engine is ubiquitous. Its current incarnation (Unreal Engine 3, at the time of this writing) powers more than 200 titles, and it's a rare week when an Unreal Engine game is not present in the current charts. However, most of these games cannot be edited by the mod community (in fact, only Unreal Tournament 3 boasts complete mod support, although some other games have level editors available).
Unreal Tournament III
The Unreal Engine has been around in one form or another for nearly 15 years, and with this longevity comes a wealth of documentation and a community that is both uniquely helpful and uniquely creative. Unreal boasts a wide selection of proven industry standard tools, but does have its drawbacks; you can't access the Unreal Engine code at any level other than UnrealScript, which is enough to change gameplay mechanics but not really powerful enough to build completely new features or integrate external libraries (without a lot of extra work, at least).
Nowadays, many modders are using Epic's Unreal Development Kit (UDK), a more up-to-date development platform for the Unreal Engine that is free for noncommercial use and comes with indie licensing terms and multiplatform support. For designers or those who just want to mess around with levels and concepts though, working with Unreal Tournament 3 can be a good way to see the nuts and bolts of both the game and engine in action before moving over to the UDK.
Moddable Games: Unreal Tournament 3, Roboblitz
Level-Editor Only: Gears of War, Mirror's Edge (unsupported)