My Home campaign is set in a Roman like Empire. It has been the dominating power in this part of the world for a thousand years. Nations surrounding it either pay tribute and are vassal states of the Empire, or are sworn enemies, exchanging blows with the Imperial Host over and over.
The Empire seems strong, but something dark is stirring. Nobles hungry for more power, and bitter over the recent end of the Slave Trade seek to remove the current Emperor. They seek allies from wherever they can find them. Some, turning even to older powers. From this, the Old Gods, parents of the current pantheon are being awoke, or freed. Their servants while acting in line with this plot of assassination have their own goals.
What's more tensions at the borders rise, as a new green tide of Orcs and Goblins seems spurred into action from the South. The Slumbering Giants, and their northern barbarian soldiers once again raid and pillage from the North Cap Mountains. From the Deserts to the East a new an mysterious people make contact, and bring with them potential allies, and deadly foes.
I essentially wanted to set the world, safe and peaceful into turmoil. With the attacks on nearly all fronts set to occupy the Empire's legions (not to mention a possible War of Succession), it will be up to the Players to either save the people from these threats or carve their own nation from the rubble. These Old Gods have been brought back to the foreground, and with them, all their ancient servants, dark creatures of lore and myth.
It is an Open Sandbox. My players can do pretty much whatever they choose. The forces playing against their country will continue to accomplish their goals however they can, even if the players do not follow any story hooks to directly oppose them. It is still pretty early on. They only just now discovered something old and powerful which was released from a long forgotten tomb-prison, and word has only just arrived of the massacre of the Emperor and his family. They are scrambling to protect their current benefactor, the last known blood relative to his Majesty.
I want to see what they do really with this setting. I don't know if it makes my Homebrew better than a published adventure, but I certainly feel it makes it more flexible. If the players want intrigue, the coming War of Succession and play at court will be there. If they want to explore new locations there are un-mapped regions on all sides of the known world. If they want to delve into dungeons, the ruins of the past nations, and ancient tomb-prisons of the Old Gods dot the landscape. The whole Western border of the Empire is coast and islands, offering the prospect for seafaring adventure (some players are trying to start up their own Mercantile fleet/enterprise). You can stand against Giants and Barbarians. Cut a bloody swath through the coming Green Tide of Orcs and Goblins. Even discover the forgotten past and mysterious origins of the particular breed of Humans that founded this Empire, under the forgotten labyrinthine catacombs that lie under the Imperial Capitol.
I think that is what makes me enjoy it more than an official adventure. A wider range of possibilities. Especially for players new to D&D, and who have yet to learn exactly what they want or enjoy out of a campaign. Heh. A Golden Coral of a campaign, if you will.