Dimension 3

Dim3 is a free and open-source engine for creating 3D games. Some of the engines features include shader support, per-pixel lighting, bump, and specular mapping, real-time lighting and/or baked lighting, particles and other special effects, skeletal animation and customization through javascript.

Klink! Software[klinksoftware.com]
Dim3 Forums[klinksoftware.net]