For the current project, I'm constantly on the fence on how to distribute the game. Should it be a full game in one foul swoop, or should it be sold in episodes. Of course, episodic works best for games with overlapping stories and not sure how it would go for an action scroller. But if that story is there does it really matter what genre the game is?
An episodic game also has the advantage of learning what the player expects in following episodes (through comments, forums etc.). So in a way, the players have input into helping the game improve with each release. And this will give the player a sense of some kind of ownership to the game.