Deus Ex: Breach was originally released as a part of Deus Ex: Mankind Divided as a sort of "arcade" take on the standard gameplay. It recently became its own standalone free-to-play game on Steam, though judging by the user reviews its still about as far removed from Deus Ex as it gets.
However, it appears that Eidos Montreal has a lot more faith in Deus Ex: Breach than the community given that they have just released a rather sizable update. It has brought with it randomly generated Ghost Networks that rotate on a daily basis, 11 all-new Picus Corporation maps for players to toy around with, a new conspiracy surrounding the very same Picus corporation, and naturally, a whole bunch of cosmetic items as well. The only catch is that you will need to solve all previous cases before attempting to do the Picus conspiracy, but that shouldn't come as much of a surprise given that its the continuation of a preexisting story.
And finally, if you're wondering what all of this might look like in action, here's the recently posted trailer showcasing the new maps and cosmetics. Have a look: