When a writer is writing a story, no matter the form or genre, there is a critical element to the story. The writer must know what her characters want. The writer must convey those desires to the reader clearly and as early in the story as possible. If it is a murder mystery, the detective wants to discover the killer and the killer wants to get away with it. In Game of Thrones there are a bunch of characters that want to be the ruler of Westeros.
In RPG’s the adventure designer or game master has a different problem. Assuming that you believe that maximum player agency is desirable, then the game master has to figure out what the players want hence what the characters want. Sometimes the game master/designer builds adventures that have a specific goal. Go get the McGuffin, explore the valley, slay the dragon and take its treasure. Then, the game master has to create tension that will cause the players to want to achieve that goal.
You can, and I often do, just present the adventure hook. Voila! My players, being nice people, sometimes go along and decide that their characters are motivated to go down that particular dirty hole because that’s what Travis has prepped this week and they just want to play and they trust me to provide a good time. Players being players, sometimes a hook isn’t what they are interested in, I didn’t sell it well enough,the other hook that I dangled is more interesting, or for some reason they aren’t interested and the adventure gets ignored.
It is a perfectly legit thing to ask, “What do you want?” And you probably should, especially at the beginning of a campaign or before you get started. It gives you a basis to think about how to construct your campaign and as players engage more with one part and less with another, you can make adjustments as you go along. Certain games have the expectations of players built in. If you are playing Call of Cthulu, you want and expect that your character is going to go insane from the revelation of knowledge man was not meant to know or a horrible death at the tentacle of a being from beyond space and time.
The height of the game master’s craft is to figure out what your players/characters want and then offer it to them without the players explicitly telling you what that is. It is like being good at giving gifts to your loved ones. You pay attention and learn what they like. Based on what you observe, you give them something that they wouldn’t ask for but are delighted that you made the effort to figure out. You can start building adventure locations, antagonists and obstacles around the sorts of things that interest the players in your group.
Pay attention during the conversations that have nothing to do with the game at hand. Players will often talk about movies, books or music that they like. If you aren’t familiar with the particular piece of work they are talking about you can look it up. There might be something in it you can steal and put into your campaign. The player may not recognize the particular element but it will feel familiar to them and often that will be enough to keep them hooked. The player might very well recognize the reference. They will delight in the fact that you included something they love from another medium, especially if it is somewhat esoteric. It is a sort of easter egg that they figured out and that makes them feel clever.
I believe the reason why RPG’s are so powerfully enjoyable is that they can induce emotional responses in the participants. The more powerful the emotional response, the more intense and immersive they can be. Figuring out what your players want and dangling out in front of them to chase is a perfect way to build the tension necessary to produce those emotional reponses.