The touhou games are just curtain shooters, not MMOs or anything. There's two games in the Touhou series which are 2d fighters, and if I remember right, there's a soccer game which is just fucking hillarious.
For those who don't know, a Curtain Shooter is similar to the old vertical shooters such as Galaga, but focus more around a concept called Bullet Hell. This is an aspect in which a majority of the screen may be covered in bullets and you'll be required to carefully maneuver between small gaps between bullets in order to survive.
For the plot, each game kinda has a different aspect of the overall story of Gensokyo, a realm which originally was a part of the human realm but as humans deviated away from mysticism in favor of technology, they became two distinct realms. Gensokyo is where all of the world's demons and spiritual beings went after the deviation and thus is a parallel to the human world. Very few of the main characters are actually human (Sakuya and Reimu are the only two that come to my mind, though I think Marissa and Alice can be considered humans as well), but there is a wide variety of yokai and other mystics.