Insight
Adventurer
Two additional things to consider when discussing railroading and adventure design. First is of course your definition of railroading. In my experience, railroading is when the PCs simply can do nothing other than follow the GM's plot design. No matter what they do, every single option they attempt leads back to the GM's plot. This is bad GMing.
Now, with the definition described above, there are definitely some acceptable levels of GM plot design that do not forcibly coerce the players or undermine the characters' sense of free will (note that its sense of free will - this becomes important later). Certain types of adventures require the player characters to get to a certain location, since this is where the action takes place. Other adventures involving intrigue and investigation, and certainly those not location-based, can happen just about anywhere, and this allows your plot to be more flexible.
In your typical location-based adventure, expect the plot to quickly point the characters in a certain direction. The characters must get there, because that's where the action is planned to take place. I don't have a problem with the GM pointing the characters in this direction, especially if it is done the right way. I see location-based adventures as being your typical dungeon crawl. Even though you have effectively 'forced' the characters to get to your site, they have pretty much free reign of where they go once they get to the site, so the sense of free will is still there.
In a typical intrigue/investigation adventure, the players need lots more sense of free will, since they are effectively driving the bus. Things like a timeline and villains' motives need to be flexible enough to allow for expected player reactions to the clues and plot hooks you dangle for them. Railroading is exceptionally evident in this sort of adventure, so extra care must be taken to maintain the characters' sense of free will.
So you might be wondering about the difference between the characters' free will and the sense of free will, other than my proclivity for italics. When I speak of true free will, its the decision to take a left or a right, whether or not to use a certain spell to defeat a villain, and whether or not to heal someone now or wait for it to get 'really bad'. The sense of free will is a mechanism used in plot design that takes the characters' motivations and uses them to give the characters a reason to pursue your adventure.
In order for this to work, the characters need to have motivations, and hopefully something beyond a lootin and a killin. Real character motivations make much more interesting grist for the GM/adventure author. The idea here is that you make use of these motivations in terms of your plot design - weave them into the story and involve the characters deeply enough in your adventure that they willingly undertake the paths you have laid out. This is not railroading, but making use of characters' personalities and having the characters drive the game, not the other way around.
In a published adventure, this is much more difficult, since you are speaking to a much larger audience than a typical gaming group. In order to affect a sense of free will in a published adventure, some of the previous posters have mentioned using mutliple plot hooks. What I would do is create plot hooks for many different types of archetypal player types, and work it from there - for example, your hack n slasher, your researcher, your talker, your investigator, etc.
Now, with the definition described above, there are definitely some acceptable levels of GM plot design that do not forcibly coerce the players or undermine the characters' sense of free will (note that its sense of free will - this becomes important later). Certain types of adventures require the player characters to get to a certain location, since this is where the action takes place. Other adventures involving intrigue and investigation, and certainly those not location-based, can happen just about anywhere, and this allows your plot to be more flexible.
In your typical location-based adventure, expect the plot to quickly point the characters in a certain direction. The characters must get there, because that's where the action is planned to take place. I don't have a problem with the GM pointing the characters in this direction, especially if it is done the right way. I see location-based adventures as being your typical dungeon crawl. Even though you have effectively 'forced' the characters to get to your site, they have pretty much free reign of where they go once they get to the site, so the sense of free will is still there.
In a typical intrigue/investigation adventure, the players need lots more sense of free will, since they are effectively driving the bus. Things like a timeline and villains' motives need to be flexible enough to allow for expected player reactions to the clues and plot hooks you dangle for them. Railroading is exceptionally evident in this sort of adventure, so extra care must be taken to maintain the characters' sense of free will.
So you might be wondering about the difference between the characters' free will and the sense of free will, other than my proclivity for italics. When I speak of true free will, its the decision to take a left or a right, whether or not to use a certain spell to defeat a villain, and whether or not to heal someone now or wait for it to get 'really bad'. The sense of free will is a mechanism used in plot design that takes the characters' motivations and uses them to give the characters a reason to pursue your adventure.
In order for this to work, the characters need to have motivations, and hopefully something beyond a lootin and a killin. Real character motivations make much more interesting grist for the GM/adventure author. The idea here is that you make use of these motivations in terms of your plot design - weave them into the story and involve the characters deeply enough in your adventure that they willingly undertake the paths you have laid out. This is not railroading, but making use of characters' personalities and having the characters drive the game, not the other way around.
In a published adventure, this is much more difficult, since you are speaking to a much larger audience than a typical gaming group. In order to affect a sense of free will in a published adventure, some of the previous posters have mentioned using mutliple plot hooks. What I would do is create plot hooks for many different types of archetypal player types, and work it from there - for example, your hack n slasher, your researcher, your talker, your investigator, etc.