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. 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.

It is revealed in several videos from SXSW that the level numbering is "D-1" through "D-30", implying that Danger Zone is a nonsequential episode.

Read more: http://www.angrybirdsnest.com/angry-birds-space-gameplay/