Towers of Sifnos Gameplay - Raise The Beacons, Defend the Island!

About Towers of Sifnos, from BoardGameGeek:

Following the aftermath of the Samian invasion, the Greek inhabitants of Sifnos sought to better defend their mineral rich land. Over the course of several centuries, they constructed a network of over seventy beacon towers scattered across the small island. This system would allow them to quickly communicate a variety of messages, and most importantly, warn of incoming sea invasions. Now's your chance to step into the role of an ancient Greek military commander! Prepare your people against raiding pirates by constructing towers, mustering soldiers, and investing into the future of Sifnos. Your goal in Towers of Sifnos is to have the most victory points (VP) at game's end. Points are primarily gained by increasing your influence and successfully defending the mining operations of the island's three predominant minerals: gold, silver, and lead. Players track their influence over these minerals on their player boards. Several invasions will occur over the course of the game, granting players the opportunity to prove their proficiency and might. After each invasion, the pirates will either grow in number or much needed allied reinforcements will arrive. The game ends immediately after three waves of reinforcements have arrived at the island. -description from the publisher