Improvisation

I improvise a fair amount while GMing — I usually do whatever prep I'm going to do, and then react to whatever the PCs do with whatever tools I have available.  (A random name list is essential, particularly since I appear to be consulting notes when referencing or generating names, so this NPC appears Important™.)  It's why I dig the mid-part of a campaign: in the beginning, you have to establish lots of facts and generate content, but in the middle, you're just riffing off whatever has already been established.  I'd be hard-pressed to say how much of what I run is improvisation, just because it doesn't feel like it; I'm just running off facts that have already been established, and bringing in new information as needed.

So I was pleased as punch about a month ago when I managed to run a session almost totally on the fly.  (I used to run like that all the time, but it doesn't happen as often anymore.)  I'm running Frostbitten & Mutilated, and in the previous session, my players accidentally unleashed a demon that rampaged across Rottingkroner.  They subsequently decided that the road to Nornrik was a better place to be than in the city, so they fled.  So all my prep involved generating some notable sites along the western road, and then letting random encounters do the rest.  (Based on my map, the north road leads to the hexcrawl in the book, while the west and south roads lead to Nornrik.  The south road curves around a mountain range, and so is longer but safer; the west road cuts directly through the mountains, but is less-traveled and more dangerous.)

They head west.  They meet a new PC (playing the Doctor class from The Undercroft), bandage their wounds from fighting in the city (and so stop, only a couple of miles outside Rottingkroner), and are just in time to get slammed by an ice storm.  They camp, and first thing in the morning, a frost giant rolls up.  Three PCs — including the new doctor they just met! — die in the carnage, while the survivors and their hirelings flee back to Rottingkroner.

That's where the improvisation starts.  One PC wants to start robbing houses to build up their finances for another expedition, and so sends the sneaky little pixie to investigate the wealthier houses in town.  A roll on a random table yields a diorama of a recent battle the PCs had, which is clearly going to be the fight with the giant.  I like that result because I also know it will entirely creep them out and inform whatever they do next.

While the pixie reports back and the new PCs show up (and I think there was pizza in there somewhere), I consult some more random tables, this time from Vornheim.  (It sounds like they're gunning for patronage from this obviously weird, rich person, so I know I'll need them fleshed out.)  A couple of rolls, a roll on a random name chart, and suddenly I have the owner.  (And I happen to have an appropriate picture on hand, which I think really sold the whole thing.)  Another roll for a random quest element mentions something about an ossuary holding demon bones, which sounds sufficiently like Elzemon and the Blood-Drinking Box from Chaos Rising to merit its inclusion.

I have all that done by the time they decide to show up at the house and confront this lady, and so they meet the beautiful and mysterious Bera Saemundsdottir, who is clearly using her husband's money to research occult subjects.  (One of the PCs seemed to really hit it off with Bera.)  She wants this dangerous box retrieved from a rival, and the PCs agree to it.  (And now are trying to figure out how to rope in hirelings to feed blood to this damn box.)

As far as I can tell, none of the players noticed the changeover.

There's a Mike Mearls bit where he talks about the GM being the most engaged when the player characters change plans or mess with stuff, and that's absolutely true.

I was incredibly engaged the whole time, and now the PCs have a potential new contact and patron (provided they don't screw it up).  Hopefully it works out as that patron will probably be important for some of the other stuff they've set in motion, but have not yet encountered...

(For that matter, November was a good month for improvisation and staying totally involved as a GM.  As noted earlier in the month, D&D got so crazy that I was completely engaged for most of that session, and I even had to improvise a dungeon when a teleport went awry.)