The battles are fought in real time, so you'll have to command your troops strategically if you want to defeat all the enemies you encounter as you play.
Although in-combat decisions are the most important part of the game, you also have to manage resources and plan strategies beyond these battles. For instance, you can burn your enemies' fields so their soldiers starve to death, or use the sea to your advantage.
Hegemony: Philip of Macedon is an entertaining strategy game. Interestingly, it was developed by a small team of only five people.
You can only play the first battle.