The cast is the tutorial
The Driver is you. Carissa Ward is the hero you accidentally hit — her training is why your hits matter, since every pedestrian you isekai strengthens her side of the story. The buff elf girl in your head holds your soul debt, which is the narrative reason your truck keeps working jobs. The Skeleton King is the villain threading both worlds together.
It is a tidy structure: every absurd joke doubles as an objective. Deliveries exist because of the debt; the isekai hits exist because of Carissa; the boss fights exist because of the Skeleton King. Nothing in the loop is decorative.
Two worlds, one driving model
The campaign hops between the real world and the fantasy realm, and the appeal is that your driving adapts to both — the same arcade handling, two very different sets of obstacles. For an OVA-sized game, that variety is the difference between a one-joke novelty and something you finish.
Strange Scaffold has a track record of committing this hard to a bit; here the bit happens to have wheels.