Snake Trains take you from point A to point B. They exist in your world for those time where you party wants to go somewhere and you have no idea what's in between where they are, and this new place. They're big snakes. And trains. Kinda like the catbus from Totoro but moody.
The first issue is a free, 8-page supplement detailing 5 passengers on the train, what the train actually does, and the first stop on this new journey your party is taking.
You can download the free pdf here.