The following is an idea I came up while discussing the merits of hexcrawling using a established mileau such as Mystara as opposed to hexcrawling through Terra Incognito.
So you have a traditional old-tyme sandbox hexcrawl game. You have the city of Whiteplainrockeagle and the associated megadungeon of Castle Whiteplainrockeagle a short walk from the city.
Surrounding these environs are the howling wilderness, which is the traditional Wilderlands - Post Apocalyptic OD&D environs.
Even though the players begin in an established civilized community they don't have a map of the surrounding region. Maps aren't available.
People do travel through the wilds, and there are other communities, but the layout of the land is not common knowledge. Most people never travel more than five miles from where they were born, the wilds are full of savage dangers, and the merchants that travel from city to town to city in armed caravans jealously protect their proprietary knowledge of travel routes.
As far as the PCs go, once you travel out of line-of-site of the Free City of Whiteplainrockeagle for all intents and purposes you are in Terra Incognito.
They players map the wilds as they travel through it, and as....
a) There aren't maps of the wilderness
b) There's no commonly known body of lore about the features of the wilderness
Than it follows that the features of this wilderness are unnamed.
The PCs would be the ones that would name the various forests, rivers, mountains, etc. that they come across.
Which would be pretty damn cool!
Also, Check Out These Awesome Lurid Eighties Tunnels & Trolls Solo Adventure Covers (color ones starting at the third row down). I would love to see OSR products with similar cover styles! One of the Goodman Games DCC adventures has a similar style.