In order to make a better game experience, scenes which would obviously be good to play but which aren't in the film have been fully created for the game. So while the books (and film) begin with Lyra creeping into Lord Asriel's office and hiding in the cupboard, the game has you playing a stealth and balancing section from Lyra's bedroom and across the rooftops of Jordan College, manipulating a few characters who spot you.
We also saw examples of how Shiny have tried not to go down the obvious route of using cutscenes to fill players in on the plot. In one level, Lyra is on the roof talking to Roger but the lengthy dialogue is broken up by being able to catapult missiles at passers by below as you listen.
Lyra isn't the only character you get to play in the game either. Her demon Pan and polar bear pal Iorek Byrnison are also playable in certain levels. Broadly speaking, Lyra's levels are more about exploration and interacting with characters, Pan - and the four animal shapes he can become - is used for puzzle solving and Iorek is all about full-on armoured bear combat. From slashing up daemon wolves to kill their Tartar nomad owners, to crawling through vents at Bolvangar, everything we love about the book is here. And yes, you do get to use the alethiometer to find the answers to all your questions.