What can and cannot be changed about the Halflife game with a mod?
Can I change:
.. the way things are rendered?
.. the physics?
if I can't change the way they do it, is it possible to create and call my own functions to use for physics instead of there's?
I'd like to start out by using what they've got and slowly changing everything until my mod doesn't behaive or look like the traditional halflife mod.