Crazy Taxi: Fare Wars (known as: Crazy Taxi: Double Punch in Japan), is a PSP game, which is a port of both Crazy Taxi and Crazy Taxi 2. There is also a multiplayer aspect which was not available in the games' predecessors, where players compete against one another for customers and fare money. The game was developed by newly created Sniper Studios.
Crazy Taxi: Fare Wars combines both Crazy Taxi and Crazy Taxi 2 with new features that allow players to interact with their opponents in brand new ways unseen on other systems. Giving players the ability to play wirelessly with other PSP systems nearby through Ad-Hoc or game sharing. Players can ram their opponent's cab to steal their fare or use the new interference feature to make them crash or slow down their fare delivery time.
Crazy Taxi: Fare Wars gives users the ability to record about 80 seconds of gameplay footage and then transfer it to a computer for media uses. Another feature unseen in previous Crazy Taxi games is the ability to play any MP3 files stores on a memory stick, in the game. Almost all of the sound effects have been re-recorded and are completely different than older versions of Crazy Taxi.
The original game's soundtracks contained songs by the bands Bad Religion and The Offspring has been removed, as well as many of the real-world stores in game, due to licensing issues, though many retain the iconic designs of copyrighted stores (eg. Pizza Parlor using Pizza Hut's iconic "Red Roof" prior to 1999). However, the game allows custom soundtracks; MP3 files stored on the memory stick can be played in-game.
Other differences include the afforementioned multiplayer via Ad-Hoc wireless, and game sharing, using only one copy of the game, and the ability to record your game footage; about 80 seconds of game footage is recordable and transferable.
Source: Wikipedia, "Crazy Taxi: Fare Wars", available under the CC-BY-SA License.