Danger Zone

Danger Zone is an episode of Angry Birds Space featuring 30 extremely challenging — brainteaser-like — levels. For iOS, this episode is available as an in-app purchase, with the first level free for trial. Samsung Android users can access this episode free for 3 months from launch date. The episode is available for PC users (cost-included), accessible after passing all 30 levels of Pig Bang.

The level numbering is "D-1" through "D-30", implying that Danger Zone is a non-sequential episode.

Rovio's Description
The following is from Rovio's blog post:

"Think you can defeat THE DANGER ZONE? This special episode is filled with 30 of the most difficult Angry Birds levels EVER constructed -- we let our level designers go crazy with these ones, and they came up with some brain-wracking levels. Even some of us here at Rovio HQ, where we consider ourselves to be expert pig-poppers, have found ourselves sweating in The Danger Zone!

In other words: this area is for experts only! Think you can master it?

Note: we're working on bringing the Danger Zone to as many platforms as possible in the future, so stay tuned!"

Gallery
Read more: http://www.angrybirdsnest.com/angry-birds-space-gameplay/ and http://www.angrybirdsnest.com/angry-birds-space-now-available/