First off, kudos on getting your demo out!
Secondly, my first impressions:
1) While the models you have are good, a little bit of body diversity would probably make them stand out more. Having them have more muscles (in the case of Wonder Woman and Red Sonja, for example), or having some of them be slimmer/more slender (like Black Cat or Poison Ivy, from what I can see in the preview image) would go a long way to making them look more unique. As it stands, they kind of all have the same face and body type, only with more or less breasts.
2) If English isn't your first language, I suggest getting someone to proof-read your scripts for the game before publishing updates, as that will help your story stand out from the dozens of poorly written games already on the site.
