Although it's the only one in its kind, it has a lot to offer. If you are looking for a relaxing simulator here it is
Basically, you firstly receive a truck and choose a company for which to make deliveries. The game area is very big and you can very easy get lost if you dont watch out the map and the signs. All is very realistic; from the truck's behaviour to to traffic order.
This is a game that you certainly should play if you like simulators. At least try it for a bit. It's a game that can only become anoying when you crash into something o.o . It's also a very relaxing game in my opinion that you can play after a hard day, instead of the classic UT-slaugher-yoga session. :)