[In this bonus Gamasutra design article, academic Tolino introduces his own classification for player-generated content, explaining what makes game player-created content special -- from new levels through cosplay, glitching, and beyond.]

In October 2007, Valve released the video game Portal. The game was a huge success and was praised for its innovative game play and stunning atmosphere. Throughout Portal, a computer named GLaDOS directs the players and repeatedly promises a cake to those who succeed.

Shortly after the game's release, Portal players, inspired by the game, began posting photos of cakes (link) they had baked using an original recipe hidden in an "Easter egg" within the game. In June 2006, a video was posted on YouTube in which a person is dressed as a block from the classic video game, Tetris (link).

In the video, the person runs around in a city and tries to fit the block costume into the corners of houses and different objects, as if performing a real-life game of Tetris. In both of these examples, players used elements of the video game to create their own projects. How can these player-created phenomena be explained and classified for the benefit of game designers?

The player-baked cakes and the real-life Tetris game are examples of "ludic artifacts," player-created objects (e.g. videos or costumes) inspired by video games and posted on the internet. Analyzing these ludic artifacts can be useful for game designers, and this article will present a model for better understanding player-created content and the motivation for players to creatively expand on their gaming experience. This article will also discuss methods for designing games in a way which encourages players to not only play the game, but to transcend the video game itself and invent their own game-based creations.

First, it is important to understand what ludic artifacts are, or more importantly, what they are not. In many video games, such as Unreal Tournament or LittleBigPlanet, players are given the opportunity to create custom levels or maps. These maps, and all other forms of game content, are not considered ludic artifacts. They are confined to the game and can be described as "user-generated game content."

In contrast to that, the experience of playing a game can of course lead to the creation of ludic artifacts. A player who completes all levels of Half-Life in 45 minutes and records a video of the impressive feat could decide to share his run and distribute it over the internet. Hereto, the architecture of the game world and the player's gameplay is transformed into a ludic artifact.

The clear distinction between user-generated game content and ludic artifacts then is the location or use of the content ("non-trivial" use), ludic artifacts being generated or used "outside" the confines of the game itself. Other examples of ludic artifacts include game-related graffiti, reenactments of game scenes, costumes inspired by game characters, paper reproductions of game objects, maps of game locations, video documentation of game glitches, machinima films and music videos, comics made with the help of game engines, in-game performances and even game-related Wikipedia sites (Examples).

All these artifacts may seem to have little in common, but an in-depth study of ludic artifacts, their differences, and, more importantly, their similarities, reveals their ability to be categorized and explained. The findings of this study are especially relevant for game developers, for whom it is important to incorporate basic principles of user-generated content into their game design process.

With these basic principles in mind, the design of games would not only focus on the perfection of the gameplay itself. In addition, the game design would focus on the motivation of the players to generate their own media products by transcending the borders of these games. This would strengthen the game's community and increase the lifecycle of the game -- as well as its popularity.

The questions we need to answer are, how can different ludic artifacts be described and the motivation to create them be explained, so that game-designers can incorporate this knowledge into their work? To understand ludic artifacts and map them into an understandable diagram, we need a classification, a taxonomy of ludic artifacts. Some of the artifacts created are videos, while others are drawings or even edibles. To categorize by the numerous product types (e.g. "videos" or "objects") would make comparison difficult, but a broader scope shows that artifacts can be organized easily according to motivation, into the following six categories:

• A. Competition
• B. Construction
• C. Expression
• D. Performance
• E. Community
• F. Documentation