what is the difference between this game(or should i call it map)and the original Cube 2 Sauerbraten?

Well If you see the title of this album is a pre beta progress so We didn't add so much content (except for textures and music) the models and sounds are just placeholders.

Answering your question, the physics (at the moment) are the only source code modification that Infernal Underground has... anyway it still in progress and I'm doing the best for to make this really different than Sauerbraten or other FPS (but with the oldschool style)