It was the first game in the series to offer a career mode that features a comprehensive storyline, and a garage mode that allowed players to fully customize their cars with a large variety of brand-name performance and visual upgrades. All races take place in the fictional Olympic City.

Underground 2 is the first game in the series to feature an open world, where players can drive freely around and explore the city, unlocking areas by winning races.

In Underground, you are an unnamed racer in Olympic City with your friend, Samantha. After being awoken from a daydream by Samantha, she shows you the ropes around the city's underground street racing scene. You race around the city and beat competitors left and right until you could come up to Eddie.