Instead of making the enemies get harder as you progress through the game, you could just keep them the same, but make Moonknight begin the mission during full moon, so he's at full power, and then progress through to new moon so he's at his weakest by the end.
I think this is a hard question to ask males. We think much differently. If I looked like, say, Captain America, I would love to be checked out going down the street, no matter which part of me was attracting the most attention. I have very low self-esteem, so such attention would give me a much-needed boost. I don't think women like this sort of thing though. Maybe I'm wrong, but still, I think it's a question that only women could answer with any authority.
I'm guessing this won't be subscription-based like other MMO's. I doubt any parent would fork out money for a computer game on a monthly basis. It's crazy-enough that there's even adults that do it : P