Every world needs a divine ruler eventually.
Only this one's got four contenders for the position - and you're one of them. It won't be easy. Any would be God must start capturing the planet at the dawn of time, progressively overtaking the world through the recent past, the present and finally into the future. You'll need to effectively allocate your men between inventing, mining, manufacturing, defending and attacking if you're to have any hope of succeeding. As you progress through time and technology becomes more advanced, armies can be equipped with mixtures of the weapons you have available.