Beyond one mobile game, since NetherRealm Studios was founded eight years ago, it has made nothing but fighting games. In the past, director at the studio, Ed Boon -- one of the co-creators of Mortal Kombat -- has hinted that he wants to do something else, something other than fighting games.
That said, it sounds like Boon and his team may finally be doing something new over there in Chicago.
A newish job listing (posted two months ago) for the position of Senior Artist/Animator has a pretty interesting requirement. In addition to the all the normal requirements, there's one that sticks out and that has been tucked away at the end. Right below "experience in developing martial arts fighting games," is the requirement of "experience in developing first person action games."
Now, if you know NetherRealm Studio's portfolio, you'll know the former requirement of experience in martial arts fighting games makes sense. As the developer of Mortal Kombat and Injustice, that's an obvious and likely salient requirement. But why the heck does it want someone with experience in first person action games?
As mentioned above, over the course of developing seven games, only one hasn't been a fighting game, and that was Batman: Arkham City Lockdown, which released for mobile phones in 2011. It was an action-adventure game, aka it wasn't a first-person action game. So, even if NetherRealm Studios was making another game in this mold -- which is unlikely to begin with -- that wouldn't explain why it needs someone with experience making first person action games.
All of this is to say: is NetherRealm Studios currently making a first-person action game, or at the very least, planning on making one? Who knows, but when you consider what Boon has said in the past and this job listing, it seems plausible.
In other recent and related news, a new leak suggests that NetherRealm Studios is gearing up to reveal Mortal Kombat XI next week during The Game Awards 2018. Further, said leak also claims to have the first details about the game, which include word of a new co-op mode, a handful of cut characters, and more.