The 'Plains of Eidolon' expansion for Warframe [official site] will launch on PC next week, developers Digital Extremes announced today, taking the fine free-to-play action-RPG from the confines of dungeons and missions into a new open-world zone. The Plains are big land to explore (and fly over, if you want), with baddies to fight and fishing to do. They follow a day/night cycle too, with dreadful beasties and ghosties (the eponymous Eidolons) from an ancient war awakening once the sun goes down. Hey, no one said the outside world was safe.
The Plains of Eidolon are about three square kilometres to lark about and murder in, with nastier enemies as you get deeper and those awful big'uns at night. Up to four players can adventure together, though the hub city of Cetus holds up to fifty.
Cetus is home to a new faction, the Ostrons, who have new merchants, new weapon crafting, new quests, and whatnot. Also, I'm reading that "their rich culture that revolves around the grotesque harvesting of biomechanical tissue from long-dormant Orokin Towers". Great. Lovely. What fine new friends.
Check Warframe's Plains of Eidolon page for more on everything in the expansion, including a new Focus system, a new warframe named Gara, and new weapons. Here's a big hunk of action from a September livestream: