Improvisation and randomness may lead to railroading; a pre-written story will save you

NOTE: Blogger deleted this (for bogus reasons) the first time I've posted, so I posted again with small changes. I managed to recover the comments (see below) and draft, but decided to keep this one.

This counter-intuitive, I know, but hear me out. 

We usually say that's having a prewritten story is bad form, and that you should play to find out what happens next, with input from your players and improvisation from the GM. I have advised this very thing. 

However, THE OPPOSITE is also true in one sense: a prewritten story (with beginning and end) of what happens if the PCs don't intervene is very useful.

To understand this, we have to define railroading. I wrote a post about that, but you could say that the railroad is defined by the lack of relevant choices on the part of the players. I've said:

So the railroad can happen, basically, in two cases:
Because there is no choice (for example, there is only one door) or;2) Because the choice does not matter (there are several doors to choose from, but the result is the same; or: the antagonist confronts the PCs on act three no matter what they do).

Now, if you read that post, you've seem a couple of examples where randomness takes away from player choice. If they have three doors to choose from (say, one made of wood, other iron, and other paper), but they lead to three randomly defined different rooms, the choice doesn't matter.

Well, if the players have NO CLUE and NO WAY OF FINDING ONE, their choice is random anyway, so the distinction doesn't really matter. But if they can choose to look for clues, it is better to have a these things written in advance than making them random. 

This sounds simple enough; let's talk about improvisation. 

Of course you need improvisation to run a game. After all you never know what the players will choose next.

However, relying only on improvisation is dangerous: in such circumstances, it is hard to be sure that you're not making the choices void. 

Let me give you one example. Let's say you have a cool monster (a green troll) that you want to introduce to your game. Instead of putting him in the sewers, the swamp, or under the bridge, you keep him in your pocket (or the back of your head) to use when necessary. Now, the players go to the swamp and - bam! Here is the opportunity to use your troll! But what if they go to explore the sewers instead? Well, another opportunity! The troll is the sewers!

(I think this is what Courtney Campbell calls "the quantum ogre". This link will lead to other links and eventually I find out that all this stuff has been thoroughly discussed a decade ago. Sigh. But read on).

Posted by u/MrHarakiri - source.

Now, compare this with a pre-written story or script.

There is a troll hiding under a nearby bridge. He kills the elderly witch that lives near the village. Villagers become suspicious but no one really cares about her. A week later, some sheep disappear, but the owner is a rich merchant that no one likes, so no one helps. In the following week, the troll kidnaps som children. Some brave villagers go to the rescue. Many people die, but the troll is wounded and runs away, leaving the children behind, and the village completely ruined. The end.

When the PCs enter the scene (say, looking for the witch), the story is already written (or at least outlined); as they find things out, they will create their own competing story. Or don't - they may just leave, and the story will play out as written. As you can see, the important part is that the outcome is not written in stone. Unless, maybe, if the players decide to do nothing; in that case, it might be BETTER to have the outcome written in stone so the PCs can suffer the consequences of their choice (of avoiding the problem).

BTW, I added a few prewritten endings to my own module, the Wretched Hive, before thinking about all this stuff. So here is another example from my book:

If both the Queen and Malavor are still alive, the hive expands. In 2d4 weeks, the number of demons and bee-soldiers is doubled, and the hive’s defenses are reinforced. In another 1d6 weeks, Malavor manages to mutate himself into a bee-demon, half-insane, but with full control of the bee-people. The bloated and sick avatar dies after a while, but this no longer affects the bee-soldiers, that can now be cloned in the underground. Three months after the characters left, Malavor unleashes his army against the nearest village.

In short: 

Again, we go back to Justin Alexander's definition: "Railroads happen when the GM negates a player’s choice in order to enforce a preconceived outcome".

A preconceived story is USEFUL, but a preconceived OUTCOME is bad, UNLESS it happens precisely because of the player's choices. In fact, I would say that having a preconceived story is very useful for any adventure. Just remember that the story relies on the fact that the PCs do nothing; if they do something about it, the outcome will probably change.

The term "story" has become some kind of curse word in OSR circles, and for good reason - a  story with a preconceived, unchangeable outcome is anathema to role-playing. However, once you learn this, you can safely write a story for your players to contend with - with the certainty that, most of the times, they will derail the whole thing to create an unexpected outcome.