Shifting between the dual worlds is essential and fairly novel. A massive gate or a lack of platforms, for example, may hinder your progress in one world, but switch to the other and the path may be open and clear. Ageless War looks and sounds great, but to put it simply, it's just not that fun at all. Initial levels are quite relaxing but it isn't long at all until the stages become brutal and punishing.
It's explaind during the game. But you use both Mouse and Keyboard buttons.
Always be creating villagers
Do not ignore your military
Immediately create 4 villagers
Have two villagers build two houses