In a nutshell, in 0 A.D., you start out with three things:
- Buildings, such as civic centers,
- Units, such as female citizens and male soldiers, that you can move around the map and use to gather resources, build or fight, and
- Some initial amounts of four resources: Food, Wood, Stone and Metal.
In 0 A.D., you need to gather more of these four resources, and then use them to train (create) various units at your buildings. In turn, you will need to put some of the new units to work gathering more resources and building more types of buildings. In this way, you build a strong economy with a constant income stream of all four resources, and prepare for building a strong military.
As soon as possible, you need to train a large, powerful army, that can even include siege weapons and war ships. Training each of these military units costs the resources you gathered.
Ultimately, you will send off your army to battle in an attempt to destroy all your enemies’ structures that can generate units, and all units that can construct buildings. The first player that achieves this goal, wins.