I got three words for you my friend:
Attack While Jumping
This could be a fun entry, but it ended in a mess of mechanics, and its hard to enjoy when enemies spawn EXACTLY where you jump, going through platforms could help a lot, even ghosts have problems reaching you because of that.
I mean, re-imagine this scenario as an "Endless" mode where you climb non stop while slashing ghosts without these problems, attach a scoring system to that and you got a really good game.