As the title of the game implies, you'll be driving one of five semi trucks across five stages carrying different types of cargo. As you advance through the stages, you'll have a choice between to cargo types: normal and hard (hard giving you a bigger money bonus). Each stage has different branching points similar to Outrun; take the left fork and you might go through a residential area full of tight turns while taking a right fork might lead to dirt path going up a hill.

18 Wheeler shares some similarities to Crazy Taxi in that you CAN drive as recklessly as you want - head on collisions with cars, driving into buildings, etc.