Incidently, I was introduced to Oni through Halo, though indirectly: When Halo was announced, it brought me from my rock known as "Marathon" :)--though it did not make me lose interest--and reminded me that Bungie has made & is making games beyond Myth: TFL. Thus I came to know of Oni.

The things that keep me interested in Oni are its full-contact action, and of course Konoko.
Following the precedent of Halo, Oni introduced me to true anime', and told me that Poke'mon was not representive of anime'.