if only I had three friends and the drive to see a full campaign through.

im imagining starting each player out as basically just a commoner in a tank, drafted into the war, then getting bombed into another dimension. use the first fight to make clear to them how much of an advantage this steel behemoth grants them, while also letting the town they defended introduce them to a person of whatever class they wish to take their first level in, plus a little info giving (if they ask) about the tech level of the world, and where they might go to find folks who can help adapt their war wagon into a more sustainable mobile fortress/boomstick