Behind-the-scenes book of Portal 2 now available on Steam

We all know that Valve makes great games - but now the company has dabbled in making great books, too. Portal 2 - The Final Hours is a digital tome that will give you an "unvarnished look" behind the scenes on Valve's most recent puzzler.

Written by journalist Geoff Keighley, the book takes you deep within the top-secret studio, giving an unprecedented "fly on the wall" perspective of the game.

Described as a "staggering 15,000 word multimedia experience", Keighley details the Portal prequel that was axed before it was even announced, the last minute scramble to complete the game's story mode, and all the other fun and adventures that makes up a game's development process.

The book also features exclusive photos, interviews with the staff, videos, interactive experiences (including "How Portals Work" and a 360-degree panorama of the Valve offices). Promisingly, the official description also features "other surprises".

For US$1.99 at time of writing, we think that's a surprise we can afford to enjoy via Steam - or, if you'd prefer, you can grab the digital book for your iDevice through the App Store.

Thanks, Blue, for drawing this to our attention!