In a lot of ways, yes it is. But that's where theory and practice diverge. Could all the current systems of DF be implemented anew in a way that easily scales to however many CPU cores are available? Most likely in some way yes they could be. Could the current systems as implemented be ported to better scale with the number of available CPU cores? Questionable.
Game engines are incredibly complex -- there are usually dozens if not hundreds of systems interacting with each other. Over time, this all ossifies to the point where making changes to one system requires changes to many other systems. This is kind of a fact of life with almost every game engine or codebase that I have encountered, worked with, or heard of. When you start getting into more than a decade of development, there are going to be a lot of tangled systems that are going to be very difficult to pull apart.
Yes, the fundamental problem may be solved for multiple threads, but DF solved it for one thread, and that solution is part of what makes DF fun. Messing with that solution is asking for trouble.
Just because something uses a grid doesn't mean it's a cellular automaton. You can probably write DF as a cellular automaton but that's probably not what happened.
If dwarfs have x,y coordinates that mark their position and the coordinates are changed when they move then it would not be a cellular automaton.
A cellular automaton would take a cell and look at surrounding cells to see if there is a dwarf that wants to move to the currently processed cell and switch the current cell to a new dwarf cell. The dwarf cell would see that the dwarf can successfully move and delete the dwarf cell.
I think individual dwarves could still be modeled as cells, if there was an additional layer (or a single cell?) holding their future actions.
The automaton would lose the nice property of being spatially isomorphic to the screen, and the possible states would explode, but if my understanding is correct, it could still be a cellular automaton.
Forgive my ignorance, but do you have any good references to multi-threaded cellular automata implementations? This is something I've been dabbling with myself.
You have two grids. Clear grid 2. Go over grid 1, calculate the new state for the current cell, write it to the second grid. At the end of a step you swap the grids.
Just slap on a good old "#pragma omp parallel for" with OpenMP (a nice guide is here [0]).
