Free-to-play team shooter Dirty Bomb never drew the crowds it deserved. Slightly wonky business model aside (now no longer an issue – the game is proper-free now), it was fast, satisfying and skilful stuff. Not surprising, as developers Splash Damage are as veteran as they come – they’re the crew behind the excellent Wolfenstein: Enemy Territory back in 2003, and several iterations on the formula since. They’ve got a lot to teach, and have released their original design document for the game (formerly exclusive to Kickstarter backers) free for all. Grab it, an art-book and the game’s soundtrack here.