The Source engine is a 3D game engine developed by Valve Corporation. Its unique features include a large degree of modularity and flexibility, an artist-driven, shader-based renderer, accurate lip sync and facial expression technology, and a powerful, efficient and completely network-enabled physics system.
It's not Left 4 Dead, but it's still worth trying out! Shaders, source code and tools have all been updated.
Now its January, and much time has passed, so here it is, a little news about whats going on with the mod.
Noesis provides Video Courseware for students and professors
Texturing, modelling and animation tutorials now available!
Nothing Much done as of yet. Help is needed if you wish.