In the action MMO Marvel Heroes 2015, the Danger Room has been released and brings new content. However, the relaunch for Marvel Heroes 2016 will take place next year.
The Danger Room serves as a simulation chamber for the X-Men in the comics, essentially like a huge holo-deck. With a few keystrokes, you fight against overpowering opponents in various scenarios.
In the video game, the Danger Room is a new endgame activity featuring randomly generated levels, missions, and bosses. At level 60, Beast will introduce you to the Danger Room. In a comprehensive FAQ on their site, the developers explain the ideas behind it: The Danger Room serves as a “template” for various scenarios and is meant to provide a slightly different challenge, never the same.

Well, later they want to deliver unique scenarios – so-called “special missions.” However, these will only be unlocked when players are accustomed to the Danger Room and they are sure there are no issues.
Additionally, in the new mode, you can also earn “Merits,” which can be exchanged with special vendors.
In the meantime, they have actually introduced the heroine Magik into the game (after Blade). She is also part of the X-Men universe.
The big “relaunch” as Marvel Heroes 2016 has now indeed been postponed to 2016. It is expected to be ready in January 2016. Gazillion assures players: Everything is fine, we just want to make sure it’s perfect.
The launch of Marvel Heroes 2016 has moved to Jan. 2016. Everything new is in great shape – we just want to make sure it’s perfect for you.
— Marvel Heroes 2015 (@MarvelHeroes) December 2, 2015