A game like Wolf:ET for example. For starters I assume all the models would have to be redone at a higher poly count using more sophisticated modelling an animation software, with better lighting effects than they had back 10-15 years ago?
I take it the rendering engine would have to be overhauled if you did this?
How about integrating say Bullet physics into the game, again I assume you just couldn't do this with the current engine?
What could you actually do to completely overhaul the game, graphics, particles, physics, maybe adding vehicles, planes etc..