By "improv" I mean running a session with zero planning beforehand, going totally off the cuff?

Do you do this most of the time? Half the time? Regularly? Very rarely? Or never at all?

Once I get the campaign world devised, basically all the time. Planning ahead is pretty much useless, as the stuff I come up with on the fly is almost always better than anything I thought up beforehand.

Pretty much all the time, but I think I could prep a little more. I'm not thinking of much, just a few notes would do the trick.

All the time.

I might think through what might happen if the PCs take the most obvious route whilst cycling home from work on in the shower but very unlikely to write it down and chances are they will take previously unconsidered option 5.

If I am running for a Con I will prep all teh PCs with their skills and have a plot in mind, Con games benefit from more structure.

If I was starting off a new campaign I would design the setting framework, much like the pocket settings I posted on the design forum, I will do more of those.

As I have noted before I have even designed the genre, game system and rules at the table through a conversation with the players. Then as they make up PCs using the system we just created I think of a suitable adventure. These things aren't just one offs either they can run for months once they kick off is the players are enjoying it.

Most of the time I do minimal, sketchy prep, or no prep at all.

Sounds like my answer is pretty much on par with the others. I have to do more prep to start a campaign, but other than having a few maps and such most of my sessions are done more "on the fly." I may have a general plot arc in mind, but often the game doesn't follow it very closely. It all comes down to player actions.

Depends greatly on what the group wants to do. If they are wanting to explore a module or specific plots then I improv when they do something that calls for it. Or improv the plot they have initiated. Which is often.

Example: One of the players wants to try and overthrow the local baron. So I work out who this person is, motives, wheres the baron lives, possible cronies they may meet there etc. And then improv based on what the group does thereafter.

Other times I just have a base outline of plot hooks and see where the players go or not.

Example: Rumours of Orcs in the swamp. Increase in thefts locally, strange lights reported at a mountain, Merchant is hiring adventurers for a caravan trip.

But then I might be in the mood for total freeform and just react to what they are doing.

Example: Much like the first example. But with no pre-planning.

And sometimes I set up some events that will happen no matter if the players participate or not. If they dont then its just local news that might or might not impact them later. Thus the world around the characters is more alive.

Example: Orcs are setting up a base in the swamp. They dont have any interest in the local town the PCs base from. They are prepping to battle another tribe of Orcs who have been occasionally raiding locally. Assuming the PCs dont wipe out one or both groups, they might later come across a deserted and sacked Orc village in the hills.

85%  Even running a set adventure like B2 is mostly improv.

I am surprised about the answers.
I never run a session unprepared.

That's not to say that my sessions are pre-planned, quite the contrary. A given session may in fact be improvised if players "deviate" from the material that I have prepared, but in that case I have at least something to fall back on, and extrapolate from.

In a long campaign the prep is considerably less than with one-shots, since much of the setting is already defined and npcs still follow their relative agendas.
But even then, I don't run anything without further prep.

More often than I'd like. I prefer planning properly, but I often resort to a quick read through, hastily scrawled notes or just running the whole thing on the fly.

I generally spend all my prep time at once, before the campaign starts. I maintain - update NPCs, maps, and notes - usually during or right after sessions, while things are fresh in my mind. I do virtually no prep otherwise.

GMing, or the art of playing the Rest of the World, is almost always 50% or more improv.  I don't care how much prep you do or where the players are.  Even in the most controlled of circumstances (our friendly dungeon), we try to meld the unexpected actions of the players with logical seeming responses from the Rest of the World on the fly.

I enjoy have a lot of notes and stuff pre-set; I believe that the more preset information you have, the more you have to riff off of, and the more consistent and connected the game seems.  Every GM is a builder, the better the tools, the better the created structure.

These days I get a decent amount of prep done, though no where what I'd like.  I like writing all my own adventures and how they fit in with each other, I have a large game wiki that I add to.  And the more social interactions and political the game, the better one's note taking should be, and updating.

Quote from: flyingmice;735819I generally spend all my prep time at once, before the campaign starts. I maintain - update NPCs, maps, and notes - usually during or right after sessions, while things are fresh in my mind. I do virtually no prep otherwise.

that counts as more prep than many.

Quote from: RPGPundit;735793By "improv" I mean running a session with zero planning beforehand, going totally off the cuff?

Zero planning? I ran a session with just a blank dungeon map, a vague idea that it was the haunt of evil sorcerors and just made the entire thing up to see if I could do it.

Mostly I rely on my Bag of Stuff, my experience and knowledge of genre tropes, game mechanics, and other stuff accumulated over 30 years of refereeing.

Quote from: RPGPundit;735793Do you do this most of the time? Half the time? Regularly? Very rarely? Or never at all?

I would say I have a lot of high level detail prepare but make up the low level stuff on the fly.

Right now I am running my own megadungeon. I have a high level overview of what each area has. Then use random generators to make up the content, then try to make sense of what been rolled. Discarding and adding what needed to make it consistent with my vision.

All the details of what's happening at the table are all improv for me. That said, as much as I like to improv details, I plan a lot for the big picture. But hear me well here: those are really about motivations of main characters, organizations, what type of ressources they do have access to ...
I'd say I can do that in about half an hour before the game.

I'm definitly planning not for a specific story (that's what the game is about), but for a very rich and coherent world that can sustain well my players breaking parts of it. And that needs planning.