The Adventure Game Studio (AGS) engine is a freeware tool created by British programmer Chris Jones, officially released in 1999 to mimic the graphical adventure games introduced by Sierra. The first game release using this engine was Lassi Quest. The engine has since been used to introduce freeware/shareware games by a growing AGS community.
Although AGS is basically a Windows development tool and relies on the .NET framework in its most recent versions, MacOS and Linux ports of earlier stable versions exist. As of late 2010, the editor code has been made freely available under the Artistic License 2.0.