The thousand year beach - Tobi Hirotaka

In a posthuman virtual world sealed off from the ruins of Earth, the idyll is shattered by an arachnid invasion.

Designed in imitation of a harbor town in southern Europe, the Realm of Summer is just one of the zones within the virtual resort known as the Costa del Nmero. It has been more than a thousand years since human guests stopped coming to the Realm, leaving the AIs alone in their endless summer. But now all that has come to a sudden end, as an army of mysterious Spiders begin reducing the town to nothing. As night falls, the few remaining AIs prepare for their final, hopeless battle. War between the virtual and the real begins in book one of the Angel of the Ruins series.