Warframe is, by and large, a lobby-style MMO where teaming up or starting missions was done solely from the confines of a spaceship which dropped you into a single map. With the Plains of Eidolon update, however, the lobby is going away as the action MMO gets its first open world zone.
The Plains of Eidolon will let players of Warframe experience a new area and all of its content in their own time and manner. Players are free to alk the land or use their Archwing to traverse the open landscape. Mission content in the update will involve time-limited objectives that can offer rewards such as items to build new Warframes, weapons, and more.
Exploration of the plains can also uncover caverns, camps, and other spaces where players can harvest materials, and certain areas on the map will have unique patterns that have to be traced with a mining laser to extract unique Arcane Gems.
On top of all this, Eidolons will roam the plains, which are immense constructs that are looking to rebuild themselves. These titanic foes will only attack when provoked, but will call in assistance from “Spirit” friends and will focus primarily on immense AoE attacks. In addition to Eidolons, standard enemies wandering the plains can also call in reinforcements through the use of flares; what the color of each flare means will be up for players to learn.
Plains of Eidolon is due to arrive sometime in the Fall of this year. A rundown of the most recent developer livestream showcasing the update can be found here and a trailer for the new content can be seen below.