The publisher GameSamba announced on a press release last month that Tokyo Ghoul is getting a mobile game slated for 2016. The announcement also included a statement from the President of the American publisher FUNimation Mr. Gen Fukunaga:
"Since we started airing anime in last year and Tokyo Ghoul anime fans demanding a game," and added, "the second season ended and the third season will begin in 2016, and we expect that the game will grow more."
So far there is no official statement from the official studio or Japanese publishing companies, and it may be just a fault from the CEO, nothing is sure yet until the news will be confirmed officially.