So, what are your experiences with player driven campaigns?
I run player driven campaigns pretty much exclusively. There can be GM driven segments if the players actively pursue such things, but it's generally far less common than the players driving the narrative.
Do you find them to work, require extra effort, or never work?
I find they work great, and take far less work than a prepped campaign, because very little needs to be decided beforehand. I also find it's only slightly more work during a session, and far less effort than trying to steer a prepped game "back on track" as it were. I've never found coming up with stuff on the fly to be all that difficult. Whereas prepping stuff in advance drives me batty because my brain always goes off on too many "what if" tangents. I'm good with worldbuilding lore and developing situations and NPC rivalries, but coming up with a plotline for the PCs to follow drives me crazy. I also interject a lot of Burning Wheel philosophy and often have the players give their PCs goals even if the system doesn't have such things, simply because BW Beliefs and the play loop it creates is by far the most effective way of running a player driven sandbox I have ever encountered. My job as GM is to create challenges for the PCs to encounter as they pursue and attempt to complete their stated goals. That philosophy of gameplay makes running player driven sandboxes so easy I honestly don't understand why it's not the normal way of running games hobby wide. I see so many "how to make prep easy" YT videos pop up in my feed and I always chuckle to myself and think, just run it the way BW does it and it's as easy as pie!
Do you prefer them in actual practice to more directed campaigns, or vis versa?
I don't run directed campaigns because I have such a hard time prepping plotlines. I do hope to run The Great Pendragon Campaign at some point, though I have a feeling it will be used more as a framework for world events rather than a direct plotline. I also recently got a copy of Masks Of Nyarlathotep and am interested in possibly running it because I don't have much experience running horror and long form mystery games. I do worry about how to keep it "on track" if I do run it and the players go off on a tangent, so we will see if I ever do take the plunge.
Is your opinion different as a player vs as a GM?
I am okay with being a player in a directed campaign because I have much less experience as a player and to be honest, I am reluctant to "step on toes" of the other players. So if the group wants to follow the GMs prepped plotline, then I go along with it. If the other players are proactive, then I drop into a sidekick role and try to assist as best I can. Occasionally I will take the initiative to pursue something easily accomplishable so as to not hold the spotlight for too long, but it's not my normal mode as a player.