Sorry for late comment.
Yeah, I was thinking about the copyrights and also if you couldn't connect directly to the engine, it would be of little use.
However, I ended up doing the character graphics myself in Photoshop. It actually didn't take as long as I thought. About 20 characters in an afternoon. Once you are comfortable with PS, having set up the brushes to your liking, it's actually quite fast to make some low quality graphics.
Of course, my graphical skill development seems to have got stuck somewhere around me being 7 years old :p , but it still serves a purpose of injecting inspiration in the project. As well as later, if the project reaches the level when professional artists takes over, it would serve as conceptual graphics.