There actually exists a licensed Attack on Titan Video Game,
Attack on Titan: The Last Wings of Mankind. Though there is a few drawbacks, for one, its a 3DS exclusive, two, you can only obtain it through imports and the game only works on 3DS systems made in Japan, and three, from what I've heard, it only retell the events of the anime. Though most feedback I've heard from ppl say its a great game
OT:
Ghost in the Shell SAC
Now I know there already exists a game tying to series, however that game came in the early years of the PS2. I'd actually like to see an open-world style game.
Freezing
The combat ideas in the series are very interesting, I'd like to play a hack and slash Freezing Game (with customization).
A Telltale game of a Studio Ghibi Film
......this needs no words......