A game jam is a gathering of people for the purpose of planning, designing, and creating one or more games within a short span of time, usually ranging between 24 and 72 hours. Participants are generally made up of programmers, game designers, artists, writers, and others in game development-related fields.
Traditionally, video games are created during game jams; however, board games have become increasingly accepted as a medium for game development within game jams.
The term game jam is a composition of the words game and jam session. A jam session describes the musical act of producing music with little to no prior preparation in an effort to develop new material or simply to practice. In the same way, game jams are events in which game developers prototype experimental ideas into playable games.
In March 2002, video game developers Chris Hecker and Sean Barrett, interested in the capability of modern hardware in rendering a large number of sprites, worked with Doug Church, Jonathan Blow, and Casey Muratori in developing a specialized game engine capable of rendering a massive number of sprites. Hecker and Barrett invited a small group of video game developers to meet in Hecker's office in Oakland, California for the purpose of creating innovative video games using this newly built engine. Hecker and Barrett named this gathering the 0th Indie Game Jam, a game design and programming event "designed to encourage experimentation and innovation in the game industry".
Some game jams are local events, taking place in universities, conference halls, or other private spaces. The Global Game Jam takes place on the same weekend in (as of 2013) hundreds of such locations in 60+ countries around the world. The Ludum Dare is an event where participants largely remain at home, but present their efforts at the conclusion of the jam.