i found a solution for a havoc like engine.
Don't know if it will work, but it is an idea.
here it is:
lets say you have an enemy walking around in your level.
Then when you kill him, there will be a function called.
This function days to load a model linked bodyparts together with newton physics, that replaces the dead enemy with this model.
So from that point the model will fall like you are actually dead and have remade a havoc engine.
Like i said i dont know if it will work, this is my first physics script i think of.
regards,