So, after playing very intensively we managed to play through all of the campaign before the whole crazy mess of Worldcon and moving started. The way it played, and the way it is written got me thinking.
The very first thing we noticed when making characters, is that there are recommendations for suitable skills for the investigators. Also notable is the fact that the most important people in the Antarctic expedition are all NPCs. The latter is important, since it means it will almost certainly mean that the important decisions during the expedition will all be taken by the Keeper, as a NPC, not the players. Our Keeper decided that since this meant he would have to be talking to himself, it would be both silly and boring. Naturally that meant that some key personnel had to be Player Characters instead. Having taken care of that the reason for the first problem becomes obvious. This campaign have a story, a way it is supposed to unfold. Now, I'm not saying that has to be a bad thing. Most CoC scenarios are written so that it begins with a relative/friend/acquaintance of some sort call on the investigators to come and help out with something. That of course means that there is something going on, already defined, and the players are supposed to follow the trail to the end and confront the problem. I can hardly imagine investigative roleplaying being handled any other way. Still, we managed to both ride the rails and do some serious detours.
We had to go to Antarctica, and we had to investigate the mountains. Had we not done that it would not have been an adventure. While it might be fun to have a wide open space to explore once in a while, I've found that those campaigns tend to be quite meandering and without focus without the right kind of players. Having a clear set goal isn't always bad. What did make the campaign interesting was how we were all playing characters that knew nothing about the mythos. We came to the icy waste to make scientific discoveries, and while some terrible things happened, and having been slowly lulled into the feel of a scientific expedition with all the mundane tasks of such a journey, we still decided to look at it as a scientific mystery to be solved. Finally our characters could no longer deny that things were a foot of vast importance. But our first way to handle things was still to collect data and try to talk to the mysterious creatures we encountered! Having the expedition leaders out of the equation we all had our own plan for what we wanted to accomplish, and that became a new drive for our investigation. I think my conclusion is that if you make the personal goals of your character the main focus you can still play what is a very railroady campaign, and still feel like you do your own thing. Probably it will derail things and open it up into something potentially even more interesting. It was quite an experience, and my character went silently totally insane and had she survived she would have created the most elaborate mental cover up possibly denying the journey ever happened. Instead she blew herself and two traitors up with dynamite. What a way to go.