Welcome back to the world of Frontier Post. The image is progressing well and I've thought some more about the concept.
The setting is inspired by rural mid-west America during the great depression. Times are tough but the mail must still be delivered. As a new driver you must memorize routes with uncharted roads. You only have a partial map at the start and will have to rely on old-fashioned word of mouth from the locals to know the way sometimes. For example, 'take a right after hangman's bridge, if you pass a large dead oak tree you've gone too far.' You will acquire various hints like these to help navigate the uncharted areas.
The main challenge is to deliver the mail to the correct addresses within the time limit. As you progress you will be given longer and different routes to chart out. So in a sense, it's a racing game, but the course is undefined and you're racing against time and the environment.
Road conditions and weather also play a strong hand on the gameplay. For example, some roads are susceptible to flooding, some are more strongly affected by ice, and so on.
In addition to the driving mechanics you will have to maintain your mail truck with the utmost diligence. Due to the economic woes of the country the postal service can't afford new trucks, so you must keep your old wheels road worthy. Fuel basically defines your time limit, while tire and suspension wear are caused by bad roads. Not sure what other parameters might be fun to manage.
Another danger you must avoid is of course, crashing your truck. This can be done by simply driving off the road, but there are also obstacles on the road, like other cars, animals, and occasional pedestrians.
I also thought about weaving a sentimental story into the game, which is told through the mail. Based on the contents of the mail you learn about the lives of the people you deliver to and what's happening in this world.
Final update next week, maybe ;)