In an interview with Harry Potter producer David Heyman and EA game director Guy Miller and senior art director Alex Laurant all discuss the differences between the movie and the video game as well as what was expanded upon.
On what's different from the movie:
Guy: We've expanded the Prefect's bathroom area. Because it's a multi-player game and not just Harry, we had to create a contrivance whereby Harry, Ron and Hermione could all be in the bathroom together and then go off with the egg!
David: There are some new creatures: Jo (Rowling) discussed a whole library of characters that weren't in the book so we got those.
Creatures in the video game:
Guy: There's a Vampire Mosp: a sort of wasp and a moth which Jo's seen, and the Irkling out of Fantastic Beasts and Where to Find them, so we're drawing on her whole world.
Alex: Our art department had a great time working with those creatures. It's a lot of fun.
David: It's really funny when you're working on the film because you're imbuing them with feelings: what's the Hippogriff felling? What's the motivation for the dragon? You have to think these things through about these fantasy creatures and it's very important: it is a bi-ped, it is a quadroped and what about the dragon? The people who do the conceptual art are sitting there with skeletons of birds and four-legged creatures to make sure that anatomically this is viable -this is verisimilitude. I think the approach we've taken is not to make cartoons but is to make reality and yes, we might be completely mad and delusional but we think this world is real, we work as though it is real.
According to Amazon the video game will be released on November 8th in the U.S. and November 11th in the UK.