Juvenile fantasy about 3 teens from different planets

[Tabitha87]

I remember reading this book when I was younger, so probably the late 90's. It was about these three teens, two boys and a girl, who are from different planets but all get chosen and taken to a completely different planet to, I don't really remember, save the universe or something? I remember there were puzzles they had to solve, and they didn't tell their real names cause knowing s person's name gives you power over them. And the one kid came from a planet where no one goes outside, they all live in a virtual reality world. They don't even see their family in the real world, despite them being like one room over. And he's curious about what's outside so he leaves and almost gets eaten by a pack of wild dogs. It was the first book in a series and I never read the rest of them and I'd really like to. If anyone knows this book please help! Thanks