In a post-apocalyptic world that is slowly trying to rebuild itself, you play a young man setting out on his own for the first time. In a similar style to the classic Elite, you start off with a basic, poorly armored vehicle (in this case, a truck) and then what you do is largely up to you.
There is a central storyline that you can follow at your leisure, but apart from that you are free to travel around, exploring the scenery, trading between the small towns and outposts that have sprung up, taking on delivery, escort or bounty-hunting missions and fighting off vicious raiders and nomads at every turn.
You can repair and refuel your vehicle at gas-stations, take missions in bars and, as you build up your money, you will be able to upgrade your truck with a better cab and chassis and more destructive weaponry. Eventually, you'll be able to buy a whole new vehicle.
As you progress through the game, you'll find out some truths about the world and yourself, and your mode of transport will look less like a truck and more like a battleship on wheels.