Need for Speed: Underground Rivals is the first Need for Speed title released for the PlayStation Portable. It is a PSP spin-off of the Underground titles and follows a very similar gameplay style.
Race events take place only at night and players cannot access freeroam. Tuning is a major factor in gameplay; to unlock more, both performance and visual parts, players need to collect 'Upgrade Points'.
Players can either play both Underground Mode (Career) and Quick Race. The Underground Mode can be played in four difficulties. Statistics are viewable in the Driver Status screen in My Underground.
- Circuit Race - This mode is divided into four classes: Master, Novice, Pro, and Car Spec. The first three are merely race events with horsepower restrictions, while Car Spec allows only compulsory cars to take part in particular events.
- Drag Race - In a long straight race, players accelerate their car up to max speed. This mode is only playable with a manual transmission.
- Drift Attack - Players have to drift on several markers that are placed on the ground. The winner is the one that collected most drift points.
- Lap Knockout Race - Any player that completes a lap in last place will be eliminated. This goes on until one is left.
- Nitrous Run - To win the race, players need to get from one checkpoint (called "gate") to another. By passing through a gate, time and nitrous are added.
- Street Cross - Racers will drive on a narrow indoor circuit containing mostly 90° and 180° curves. Street Cross is greatly based on Street X.
- Rally Relay - Players drive two laps around a circuit. After completing the first lap, the player has to swap their vehicle.
Players don't get any benefits for customising their car visually as there's no Star Rating. Visual parts don't come separate, but in body kit sets only. However, players can now write their own lettering and put them on the windscreen, backlight, and bonnet.
Most important are performance mods, with which players can modify acceleration, top speed, and handling. Any car in this game can be upgraded to be very competitive to even the strongest production cars. After purchasing a performance part, players can install it in other vehicles without re-purchasing.
The Performance Upgrades are divided into 10 categories for a total of 46 upgrades:
- N20 System (2 normal upgrades / 1 bonus upgrade)
- Intake & Exhaust (4 normal upgrades / 1 bonus upgrade)
- Engine (5 normal upgrades / 1 bonus upgrade)
- Turbo Charger (4 normal upgrades / 1 bonus upgrade)
- Drivetrain (3 normal upgrades / 1 bonus upgrade)
- Chassis (3 normal upgrades / 1 bonus upgrade)
- Suspension (3 normal upgrades / 1 bonus upgrade)
- Rims & Tyres (2 normal upgrades / 1 bonus upgrade)
- Brakes (5 normal upgrades / 1 bonus upgrade)
- Controls (5 normal upgrades / 1 bonus upgrade)
There are 3 different levels for each upgrade in each category (except for the bonus upgrade):
- Level 1: 3,000 Upgrade Points
- Level 2: 4,000 Upgrade Points
- Level 3: 6,000 Upgrade Points
- Bonus Upgrade: Free
The soundtrack retains the same songs featured in Need for Speed: Underground 2 as well as six new songs.
- The Donots - We Got The Noise
- No Warning - Breeding Insanity
- DJ Tiesto - Breda 8pm (DJ Montana Edit)
- My Chemical Romance - Thank You For The Venom
- Hot Water Music - The End Of The Line
- Soulwax - Any Minute Now
- The Game Boy Advance and Nintendo DS releases of Underground 2 use similar gameplay mechanics as seen in Underground Rivals.