Great premise! Not sure where the theme comes in though and I found some issues in the game:
- The bike felt too slow and sluggish, especially when braking (on real vehicles braking is faster than accelerating)
- There should be engine sounds/more responsive audio in general
- Some buildings were floating off the ground
- Late deliveries did not register until the package was actually delivered (it should notify the player immediately)
On the bright side, the graphics were good and I think the game would be great with some polish. I hope you'll keep working on it.