The good news is I just picked up Ninja Gaiden Sigma. The bad news is I'm still neck deep in Odin Sphere. The pace of the two games are so different, it would be tough playing them alternately. Also, NG is the type of action game you really have to devote your full attention to. I might finish out the current character arc (The Pooka Prince) and come back to it after I finish Sigma. There is a story viewer in Odin Sphere I can use to refresh my memory.
In other Tecmo news, they just announced DOA Online for release in China. It's going to be more of a casual MMO type of deal and feature characters that are more cartoony. Bizarre.