My goal was to create a 3D point-and-click adventure game.
I totally underestimated the amount of work involved and ended up with an incomplete project. It's not even a game yet.

Some of the noteworthy features are:
-particles
-stencil mirror
-lightmap baker & packer
-a* pathfinding
-bezier curves for smoothing out character paths
-frustum culling with octrees (with polygon splitting)
-dynamic character shadows
-lua integration

Tools used: Dev-C++ (a free C++ IDE plus MinGW complier package), Blender (a free 3D modeling/animation package) and Photoshop (this one's not free).
Libraries used: OpenGL, SDL, Lua and libpng

Here's a Windows version in case you'd like to try it out:
Download (1.3 MB)
There is a file named "res.cfg" inside the archive you can edit to switch resolutions.
Unsure of system requirements. I tried it on an old system with the original Geforce and it did not display character shadows.

The following is a screenshot from a demo I made a day after the project was due, mainly to show off the flexibility of the game engine