I've been working on a (simple) first-person shooter thing for the last month or so, and as of today I believe that I have added enough stuff from OpenGameArt.org for it to be considered "presentable" (but by no means complete).

It's not very advanced - the world is represented using a list of AABB regions, and actors do not use scripts, with most of their behaviour hard-coded (but tweakable via various external files). It's more of a just-for-fun spare time project than anything else.

Here's a picture: https://sites.google.com/site/gobusto/projects/no-name/robots_30thJuly2011-1.png

...and the project page: https://sites.google.com/site/gobusto/projects/no-name

You can download the source code and a Windows executable from the page linked to above.