3DWorld
3D Procedural Game Engine Using OpenGL
...I have an old makefile that is out of date, but may not take too much work to fixup and make it usable. Realtime day/night cycle with weather (rain, snow, hail, wind, lightning). Physically based materials with reflection and refraction. Dynamic shadows, ambient occlusion, up to 1024 dynamic light sources, postprocessing effects. Built-in first person shooter game "smiley killer".