Paper Mario The Royal 64

Futaba perchases a game called "Paper Mario" and convinces everyone to play it. But they soon find themselves in another world called the "Mushroom Kingdom."

Almost as soon as they arrive in the unknown world, they're under attack by a giant turtle named Bowser, who defeats this worlds hero, Mario, and separates the Phantom Thieves from each other.

Now stuck in another world, the Phantom Thieves must reunite and help Mario on his quest to save these Star Spirits and rescue the princess and Futaba.