http://www.pcgamer.com/warframe-trailer-brings-new-plains-of-eidolon-gameplay/

Digital Extremes has released a new teaser showcasing some of the environments and action from the upcoming Warframe expansion Plains of Eidolon, which will see the launch of the game's first large, open-world "landscape." Players on the Plains will be confronted with new and old creatures and enemies, a brand-new Warframe, a day/night cycle, and "a gripping story told through interactive NPC characters who inhabit the bustling scavenger city of Cetus." 

Warframe: Plains of Eidolon will also see the introduction of the Ostrons, who scavenge biomechanical tissue from Orokin Towers, and new mission types that will enable the discovery and construction of new weapons, Warframes, and other items. "Experience a bristling new world where the wind rustles across your Syandana and the age and size of giant Orokin structures ominously looms in the background," the studio promised. "Earth will be more alive than ever before."