Just finished watching Attack on Titan yesterday and decided to start playing the game. It's pretty awesome, very faithful to the series and the gameplay is spot-on, mastering the 3D Maneuver Gear takes real effort but it's a whole lot of fun. As for the lore, it really really helps to watch the series before playing the game. I'd say that the series serves as a background to the game.
I also went out and bought Nioh & Yakuza 0, with Trump preparing the sanctions, a used copy might become even more expensive compared to a brand new copy right now.