Me likey. So far.
Only thing I would suggest--the walls look a bit bland in places where there aren't tiles defining a brick pattern. Even then, those have pretty heavy lines. Perhaps have some more small brick tiles, and/or some large brick tiles--both would have thin(ner) lines.
Now, though, the princesses' right arm, the arm we can see, seems pretty stiff. Maybe lay down some pixels defining an elbow/slightly bent arm? Same with the guard's left arm. Perhaps in a hands-on-hips sort of position, with his cape draped over it. If you don't get the idea I'll make an edit.
Other than that the plot sounds interesting. Maybe it's just me and the recent release of its sequel, but I'm vaguely reminded of Portal. (Must I explain? Discovering the darker truth out of curiosity and rebellion. Or something. On that note, you might want to make the contrast higher. A little orange or at least more contrast on the torch tiles, which also seem a bit dark considering they're a source of light, might make for an interesting touch BTW.)
