It's like an MMO... And a shmup. :0
I don't know how good it is; I've only just read about it on (link)Maidens of the Kaleidoscope (http://www.shrinemaiden.org/forum), but according to them it's pretty good. Currently downloading it, more info later >_>
Also, link.
http://valkyriesky.gamekiss.com/main.jce
Edit
Here, gameplay vid
http://www.youtube.com/watch?v=zfbQweYRzPA&feature=player_embedded