Update 2: It's on Origin now. Note that it doesn't have multiplayer co-op—only local, according to the description.
Update: Unravel 2 has been officially revealed at EA Play. Not only that, it'll be available today (we couldn't find it on Origin yet at the time of writing). The game is a co-op experience that is playable either with a friend or by yourself. All of the puzzles have been designed for two Yarnys to solve, so players can alternate between their two characters when playing by themselves.
Original Story: In 2016, Electronic Arts announced that adorable puzzle-platformer Unravel was getting a sequel, but kept all the details close to its chest. Now, Unravel 2 has an ESRB rating that hints at co-op, which wasn't in the original.
The ESRB rating says that players will "control a pair of fantastical creatures called Yarnys". It's possible that the game will still be singleplayer and that you'll control two characters at once (like in Brothers: A Tale of Two Sons). But given the unstoppable rise of multiplayer, a co-op story seems more likely to me.
The rest of the ESRB rating is as you'd expect: you'll be "swinging from yarn lassos", trying to avoid getting "eaten by a fish, grabbed by birds, crushed by boulders, or run over by cars".
The timing of the ESRB rating suggests we might find out more at EA Play later today, so stay tuned. EA is publishing the game, and Coldwood Interactive is the developer.