Armadillo adventure is an adventure game set within a world. It is a codebase, a toolkit for making your own adventures such as King's Quest. The toolkit has an example adventure program that can be easily changed and enlarged by derivation. If you are more interested in dungeoneering games, take a look at the <a href="http://freshmeat.net/projects/tanirs-quest/">Tanir's Quest</a> project.
The Brick Engine is a fast and simple lo-fi gaming engine. The engine provides a comprehensive API, including dazzling visual features, song playback, and collision detection: everything you need to make games with quickness and ease. The engine provides a straightforward C API and has language bindings for Tcl and Pascal, with support for more languages on the way.
The Kowalski project aims to provide a data driven, lightweight cross platform audio solution. The target audience is developers of games and similar applications where real time audio plays an important role. The Kowalski engine, which is the runtime component, relies only on host-specific external libraries to pass the final output buffers to the audio hardware. All other processing is done in the engine code. Features include positional audio (distance attenuation, cone attenuation, Doppler shift, binaural panning), real time Ogg Vorbis decoding, a powerful mix bus system, and tools to build, validate, and view Kowalski data.