IGN has posted a brief article discussing some of the unused concepts and scrapped ideas from the development of Revelations. Interestingly, Revelations was apparently originally going to be co-op.

http://ds.ign.com/articles/122/1220248p1.html

The capsizing ship was one concept I was looking forward to from the original teaser. Would have been a clever way to change the layout of the ship. Kind of similar to how the self-destruct blast changed Chris' route through Rockfort Island.