The Three Adventure Formats

Adventures are here defined as any way to get players talking to NPCs, fighting monsters, exploring, and dodging traps in order to get a proportionate reward.

Number One 
This is the simplest adventure format, and it's based on Gygax's random dungeon generator:

I tried to simplify his tables to just a couple q-cards.  On the left column is a d20 roll, and on the right is any increment of movement that makes sense for your dungeon.  Typically you might use 60 feet.

To use these cards, fill out a few tables that are custom-made for your campaign:

• Tricks and Traps
• Special Rooms
• Monsters 
• Wandering Monsters 
• Treasure

Number Two
Conan stories all follow one of the following formats:

1. Jailed by Wizard, Battle (e.g. Scarlet Citadel)
2. Ancient City/Ancient Witch (e.g. Slithering Shadow)
3. Tomb King (e.g. Devil in Iron)
4. Pirates vs. Monster (e.g. Queen of the Black Coast)
5. Savagery Must Always Triumph (Beyond the Black River)
6. Break & Enter on Wizard (Tower of the Elephant)
7. Princess vs. Evil Sorceror (Black Colossus)

I'll fill these out in a later post, but for now suffice it to say these stories have recognizable beats that you could use to come up with great adventures.

Number Three

This is what I'm most excited to try out.  Basically you take a world map like this:

Now this is a work-in-progress map of Gazyantep, a patchwork of city-states.  The smaller dots are cities as large as 20,000 people, the larger ones 50 to 100K.  

Population size is important because it's a really quick and easy way of keeping track of everything that's going on in the world at once.

If a city swells in numbers, those people must be coming from somewhere. Are they deserting from some other city? Are they simply flooding in from the countryside? Are they foreign traders and mercenaries?

Answering gives you adventure hooks to build off. For instance, say a player wants hirelings. A nearby city is being terrorized by a powerful mummified tomb lord. A cheap option for hirelings will be runaway serfs from the rival city, but they might be pursued by bounty hunters working for its nobility and priesthood.  

Why Cities Grow: Trade

The fastest way cities grow is through trade.

Gazyantep's riverine valleys produce plenty of food, but each city must trade for timber, stone, metal, and silk. This means that trade routes exist independently of cities - if one city falls, perhaps a nearby rival will take over its position on the route.  Perhaps a nearby town will swell to the size of a city.  Etc.

Why Populations Leave: War & Magic

Use some basic rules for loyalty/cowardice. I think Gygax has some good ones in the first DM guide.

Player-owned Towns

Eventually players will rise to positions of paramount importance, even ruling over cities, coalitions, and empires. 

At that point, fully-fleshed out rules for diplomacy, trade, and war help make it all feel like a game with proper consequences and weighed risks, rather than a railroaded story decided arbitrarily by the DM.