Fallout: New California adds an all new story around a new player character, an adopted resident of Vault 18, embarking on a journey through the wastelands of the New California Republic's Cajon Pass. An unofficial prequel to New Vegas, FPB adds hours of new gameplay and a fully voiced stand alone campaign.
An excellent modification don't get too many entirely new campaigns (story block) multi-path main quests and side quests. All this for free. Keep up the good work guys.