FOV (field of view) sliders give players the ability to adjust how much of a game world they can see on their monitor at one time. Some players will widen their view to gain a tactical edge—the more you can see, the more you can kill—while others make adjustments to combat the effects of motion sickness. (This Quake video does a good job of illustrating the benefits and drawbacks of messing with FOV.) They have value, in other words, but their implementation is far from universal. Evolve, as an example, launched without an FOV slider and then patched one in later.
Fortunately, Deus Ex: Mankind Divided will offer an adjustable FOV right out of the gate, on the PC at least. "PC version will have it," Executive Game Director Jean-François Dugas said in response to an inquiry on Twitter. That question, interestingly enough, followed a Dugas tweet from a couple of weeks ago in which he clarified a November 1 statement that Deus Ex: Mankind Divided will be locked at 30 fps:
No no and no. 30fps is consoles. We all breathe, thanks. https://t.co/uUqFQMOqkWNovember 3, 2015
Good news, that. Deus Ex: Mankind Divided will be out on February 23, 2016. It's looking very promising.