Splash Damage, developers of Dirty Bomb, have released the game design document, art book, and soundtrack for Dirty Bomb. According to their blog post:
Many moons ago, prior to the rise of Kickstarter, we launched a crowdfunding campaign for Dirty Bomb. Three of the rewards, Dirty Bomb’s Game Design Document, Artbook and Original Soundtrack were promised at the full release of the game to the people who pledged money to support the title during that campaign, our ‘Founders.’
We’ve spoken with our Founders and they respected our wish to make those three things available to everyone.
The Game Design document includes hundreds of pages of designs, sketches, notes, concept art, biro drawings, user stories and more. It can be downloaded here: link
The Art Book looks at many of the original concepts for Dirty Bomb; from maps and characters to weapons and vehicles. It can be downloaded here: link
The original soundtrack can be downloaded here: link