"The goal was to show something that they hadn't seen before," said director James Cameron.
Cameron takes moviegoers on an adventure he began more than four years ago. The result is part live action, part state-of-the-art motion-capture animation.
"Avatar" is said to have cost hundreds of millions of dollars.
"I'll tell you exactly what 'Avatar' costs: $15. Twelve if you see it in 2-D, and if you can get a senior discount, you know, maybe 6," said Cameron.
"I will never know what it takes to put these things together because so much of it happens in the NASA banks of computers," said Wes Studi, an actor in the movie.
Sam Worthington and Zoe Saldana play two characters from different worlds who feel a strong connection.
Sam acts both in the world of animation and as a human being.
"Each of the sides of the film has its own challenges but, you know, the whole movie for me took 14 months," said Sam. "The biggest challenge was Jim [Cameron] trying to get everybody and all these talented people together."
"James Cameron calls you on your cell phone, you're going to pick up that call and you're going to say 'yes' no matter what," said Zoe. "And every day, every day he proved to me that I was so happy to have made that decision."
Advance ticket sales for "Avatar" have been sold primarily to men, something the film's stars hope will change.
"And I hope a lot of women go to see the movie and I hope a lot of people my age go to see the movie because you shouldn't just go, 'Oh, it's a 3-D movie, it's for these kids or boys.' It's not. It's for everybody. Nobody should miss this," said Sigourney Weaver.
"If women don't go to this movie, they're crazy," said actor Joel David Moore. "It's a love story. That's the big secret. It's just a love story."
"Avatar" opens Friday at 12:01 a.m.