“Computer gaming seems to be very popular among F/LOSS communities: as of October, 2008 the SourceForge repository shows 29,831 game projects. Software developed in these communities includes role-playing games, simulation games, Multi User Dungeons, first person shooters, arcades, and board/card/strategy games. SourceForge’s activity rank shows that among the 100 most active projects, 7 belong to the category “Games/Entertainment”. Almost 60% of the computer game projects have end users as their intended audience. The remaining ones are software projects such as toolkits, modeling, rendering, and animation engines–frameworks that target developers.”

The above is from a cogent analysis of free/open source game development, in the following article:

Contrasting Proprietary and Free/Open Source Game Development, Alessandro Rossi & Marco Zamarian. Open Source Business Resource, October 2008.

The article compares the development process and use of tools in both open and proprietary gaming development.