Psion said:
The operative word being scenario, vice plot. The GM needs the flexibility to consider interesting events and challenges that will engage the players and manuever players into view or involvement with those. But the players, unless they are the type to "just go along for the ride", will typically require free will or the illusion of free will. Which may mean that they have the freedom to come up with their own solutions to the challenges that the GM faces them with.
Which is exactly what I do. That does not mean that I do not create a plot. Plot is essential to a good campaign. When I am writing for my campaign, I consider the character histories of my players and then weave them into the plot. In my current campaign, the players are the driving force, but I have made them want to do what I have planned, by keeping the focus on their characters, tying them into the world and background of the events, and throwing out carrots whenever possible.
They always go rushing in. Actually, I am having a lot of fun with it because they are intensely interested in the campaign. One NPC peed them off early, so our barbarian's main goal is to see him dead. It helps that the NPC has also sent assassins after them. Another PC has a family secret (that she does not know), which has really allowed me to leave clues that get her to chase them.
The great thing about last session is that they completed a major party goal. They finally got to meet the local sage (after many sessions worth of attempts and sidetracks) after they killed his apprentice (evil mystic theurge who had been keeping him locked up and enslaved for the last 4 years).
When I wanted to encourage them to leave the city, their thief found out that the local assassins guild had been contracted to take their lives and now he is the driving force in getting them to leave. (The guy is terrified of the Black Guild.)
A canny GM can direct the game toward his goals as long as he knows how to interest/ influence the characters. As a GM, I have goals. There are things I want out of the game. I can see those goals fulfilled and still engage the characters as you tie them to the events.
Granted, I did not start the game with a defined story line. It started with an adventure and it grew from there, but the game still has a plot.
Psion said:
The role of the rules here is somewhat important -- it gives the players their only reliable handle to deal with a variety of challenges. If the rules often don't behave the way they expect, you run the risk of making the players feel powerless, or being "swept along with the tide" of the GMs almighty plot and whims.
I agree. That is why I enforce the rules for encounters and challenges. I break the rules only to help provide a sense of wonder and never break them during combat etc. I like providing events that are beyond the character's abilities or that they cannot necessarily point to a rule and say "this is what he did." This usually has to do with weird magical effects or the like that have no corresponding spell in the PHB, although should they get high enough level and wish to do the research, then I can always make something up at that point.