Lee Salzman (aka eihrul), the maintainer of Sauerbraten and I spent some time working on a revamped version of the Sauerbraten engine.
Well, Lee did almost everything even if I did some parts of the snapped cascaded shadow map implementation and we got some interesting discussions about what to do.
Tesseract aimed at being a modern version of Sauerbraten engine with dynamic lighting and shadow maps for everything based on a kind-of-standard deferred shading pipeline.
This includes omni-shadow maps using either cube maps or tetra shadow maps, sunlight shadows with cascaded shadow maps. Everything uses actually a giant shadow map atlas.
Good thing is that Lee made a two-pass approach to handle and shade transparent objects (front-most layer) and as you may see here, it gives some pretty neat results on transparent / semi transparent objects.
Code is finally here: