It's been a while since I had a bona fide campaign. The odd one-off or short string of games, yes.....campaign, not so much. After a recent discussion about my old GM buddy Rob I thought a lot about campaigns in general, and then my own in specifics.
It has been my experience that most GMs....well maybe half of GMs, don't really have a solid campaign. They may have a string of themed adventures here and there, but an over-arching campaign....not so much. My buddy Topher (Hey Topher!) probably does the best job at a campaign I've ever seen. He actually polls his players on what kind of game they want to be playing in, and I've got a copy of one of his player questionnaires you can look at here.
I know of three of Topher's campaigns: One based on the Icelandic Sagas, another on the fall of Constantinople (1453), and another loosely based on Hogwarts, where all the players were different types of Magic Users where every level was a year of school. Of course, these are broad strokes of remembering and I while I have played a session or two at his table when in the area for work, I don't personally recall any first-hand particulars.
Now I mentioned Rob's campaign where we joked he could tell you how many field mice were screwing in a particular farmer's field three counties away. As much as I liked Rob, his campaign...or at least that one, felt like a railroad storytelling session where we occasionally rolled dice.
Personally I like to have an overall campaign theme and have a few initial ideas, and stuff that will happen in the background regardless of player intervention, or even notice. I try to keep things running on three levels...you could think nationally, regionally, and locally, but that's more a geopolitical hierarchy. I like to think of it as big ideas, small ideas, and something in between.
For example, my last campaign (I had a blog for it, but it was far too much work to do everything I was trying to do) the overall campaign idea was history repeating itself in that a Charismatic Half-Orc was going to unite the orc tribes and invade the region where the party members grew up. Of course they didn't know that was the "thing". The campaign world was magic-lite because magic had been gone for 10,000 years and was just re-emerging. With the return of magic came the slow return of the gods, as they are tied together.
Most of the players secretly had some measure of clerical power in the form of being able to cast one spell a day. Generally the good-aligned gods spread their power out through a number of individuals while the evil gods concentrated them in one person.
I basically drew an outline, well more a future timeline, of how the campaign's BBG would progress. When & where does he appear and how he builds his power base. The players were free to adventure as they saw fit. I mapped out logical decision points and setup some adventure seeds. I also had a hip-pocket mini adventure or three set aside in case the party went somewhere I completely couldn't fathom....as they sometimes do. I let the players pretty much determine their direction and in doing so the "small ideas" I had seeded here & there. Depending on how things played out I took the repercussions of the "small ideas" and stepped them logically to the "something in between".
In this low-magic campaign the players started off with their secret powers and they did a good job keeping those secrets, well at least initially, from the NPCs. They ended up setting themselves up as troubleshooters for the community. On one "mission" from the village Elder they came across someone else that had broken into an old tomb and come across some magic and some undead, which of course killed some PCs and freaked the one survivor out, bad enough that he broke some severe social taboos. The party caught the guy and turned him over to the Elders, who branded the guy and banished him from home....which is a big deal since few humans have been more than a few miles from home.
Now in the background the future BBG has also discovered his powers and has been using it to consolidate his power base and start raiding far earlier than expected. The party doesn't know this, of course, nor do they know that they had made an enemy of the brandished/banished guy, who migrated East and would be a future villain.....had they ever travelled East.
Instead they party decided to go West to the closest city where on the way they ran into some Halflings, which were essentially the world's travelling merchants, and discovered a network of Halfling campsites and they start learning more about this world outside of "home". There was a Goblin attack they easily repelled, but they didn't figure out the Goblins were pushed out ahead of the raiding Orcs. The party had some other adventures and eventually came back in time to discover the Orcs raiding early, which they duly reported.
While the party was doing their thing, the world was turning...with and without them. Eventually a new player stepped in and chose to be a Cleric.......and boy did that campaign change once her secret got out! The players did have an initial run-in with the BBG, but the group broke-up shortly after this initial contact.
I could go on with another campaign, but my main point is that I like to have an idea for an overall campaign, an idea that isn't necessarily communicated to the players up-front. Instead of having a scripted plan that gets checked off at the player's speed, I want things to happen regardless of PC interaction. They can interact or react as things progress, but they do have a lot of agency in the campaign. I'm not going to railroad them, but instead let them go off and "do their thing" and then adjudicate how that works into the overall story and how it helps fill in the game world.
I'm hoping this makes sense.....obviously whatever works for you and your players....well, works, but I think there is a lot to be said for having a campaign that exists with and without your players interaction.