When I GM, I generally determine who the antagonists will be, but if the players have build antagonists into their PCs' backgrounds then I follow their lead. If the players want to change allegiances during the course of play, so former antagonists become allies, or vice versa, that's fine. Changing loyalties is a recurrent theme in my game. At the moment I'm trying to tempt the Wizard/Cleric of the Raven Queen to Erathis-worship instead. In the past, I've had PCs sacrifice other PCs (with player consent) to dark gods before deciding to side with the evil cult rather than wipe it out.
Unless I have got more-or-less expresss agreement from my players (often in the first session of a new campaign, when they all meet with their patron in the proverbial tavern) I don't like to assume that they will bite at generic plot hooks. (I therefore find the setups for a lot of later TSR and WoTC modules unusable, because they assume the PCs will follow a lead which my players would never follow.) But if, for example, one of the PCs is a samurai, and his/her player has given no indication that treachery is on the agenda, then I will plan for a session assuming that if the daimyo gives an order then the PC will comply. I also tend to assume, unless I've got reason to think otherwise, that the party will tend to stick together, so if one PC has a good reason to do something (such as orders from the daimyo) and no other PC has a good reason not to, then the whole party will go along with it.
So I don't think of myself as GMing railroads, but I don't run a sandbox either. And I do tend to use the "all roads lead to Rome" technique - if it has been settled who the anagonist is, then generally the game will lead to a climax with that antagonist one way or another, although the precise nature of that climax might change depending on the events leading up to it. To this extent, at least, my games tend to exhibit a "story logic" rather than an "ingame causality" logic.
The last time I played AD&D the GM was running a bit of a railroad, but the group had about 7 players, and playing out the interparty dynamics and interacting with the scenery provided a fun outlet for roleplay and characterisation. When the GM pulled the plug on all that by teleporting us 100 or so years into the future of the campaign world, therefore invalidating all the relationships that we (as players) had built up between the PCs and various elements of the gameworld, I left the game rather than start again from scratch.
So I infer from that that I don't really like playing in a thorough-going railroad either.
Unless I have got more-or-less expresss agreement from my players (often in the first session of a new campaign, when they all meet with their patron in the proverbial tavern) I don't like to assume that they will bite at generic plot hooks. (I therefore find the setups for a lot of later TSR and WoTC modules unusable, because they assume the PCs will follow a lead which my players would never follow.) But if, for example, one of the PCs is a samurai, and his/her player has given no indication that treachery is on the agenda, then I will plan for a session assuming that if the daimyo gives an order then the PC will comply. I also tend to assume, unless I've got reason to think otherwise, that the party will tend to stick together, so if one PC has a good reason to do something (such as orders from the daimyo) and no other PC has a good reason not to, then the whole party will go along with it.
So I don't think of myself as GMing railroads, but I don't run a sandbox either. And I do tend to use the "all roads lead to Rome" technique - if it has been settled who the anagonist is, then generally the game will lead to a climax with that antagonist one way or another, although the precise nature of that climax might change depending on the events leading up to it. To this extent, at least, my games tend to exhibit a "story logic" rather than an "ingame causality" logic.
The last time I played AD&D the GM was running a bit of a railroad, but the group had about 7 players, and playing out the interparty dynamics and interacting with the scenery provided a fun outlet for roleplay and characterisation. When the GM pulled the plug on all that by teleporting us 100 or so years into the future of the campaign world, therefore invalidating all the relationships that we (as players) had built up between the PCs and various elements of the gameworld, I left the game rather than start again from scratch.
So I infer from that that I don't really like playing in a thorough-going railroad either.