I think it would be interesting to add some kind of signal in the corner of each stage (or when the person moves the mouse over), indicating how many points above the 3 stars one could do. That way it would be easier to select the levels where a person did better to try to get more points and get the impossible badge.
So I was on level 10, I killed all the monsters, I went into the dungeon, I killed all the monsters, I came back, I was going to level 11, but a warning says I do not have the golden key to pass the level. I'm sure I caught her, but she disappeared. Unfortunately, when I try to take it from another level and go back to that level, it disappears as well. I'm going to have to start over, is that it?
Just a tip to the dev. (don't kill me): there should be an option for really, really slow computers, like mine. Even with all colors, sounds, FPS, changed, it's still laggy. :/
Just one thing ~please don't kill me~ I think you guys could put the total combos and missions, because it's a little bit frustrating when I achieve a 200 combo and the max number rises to 400. T_T