In this game, you play as Neku Sakuraba, an anti-social boy (at first anyway) who is dragged into a game of life and death. He has to stay alive for 7 days in a game, where the losers are 'erased', completing missions within time limits.
However, he doesn't remember anything. Other than his name, he doesn't remember anything. Why he's in the game, how he died, etc... and also, the fact that he's dead. The setting is in Underground Shibuya, where people who have died gather to play this game. The winner(s) get to be revived and live again.
He doesn't do this alone though. Players need partners to survive and fight the 'noises' (think random battle like in other games except that in this game the battles aren't random).
The battle system features a new way of battling. Using the touch screen to control Neku, you use the d-pad or the XYAB buttons to control your partner. Both attacking and avoiding attacks with Neku are done using the touch screen. Avoiding attacks with your partner is done by either jumping (up or X) or blocking/avoiding (down or B). Both characters share the life bar and you lose when the life bar drops to 0. They do no have separate life bars, this can be considered as a good or bad point depending on the person.
This game is really popular, cited from wikipedia:
Overall, The World Ends With You has been well received among video game critics. Many critics note the departure from other popular titles such as Square Enix's Final Fantasy and Kingdom Hearts series. Thunderbolt gave the game a rating of 9 out of 10, citing its refreshingly original story, integration of urban culture and spiritual myth, and intuitive, fast-paced combat via the touch screen; while bringing up the aforementioned differences between it and other Square Enix games. GamePro also awarded the game a 9 out of 10. Game Informer gave the game an 8.25 out of 10 along with the Handheld Game of the Month award for May 2008. IGN has given the game three different reviews, each from a different regional branch (UK, US, and AUS), and scores of 8.9, 9.0, and 9.1 out of 10 respectively. All three have awarded the game Editor's Choice Award. In addition, X-Play gave it 5 out of 5 and called it a "must play" DS game. This is the first DS game in almost two years to get a perfect score from the show. The last game awarded this score was Mario Kart DS.