I hope you don't mind me making a mockup of your work, I just couldn't resist:
This animation shows the difference between the dark and lighter outlines, as talked about in this thread, in a mockup.
I added dithering to the house in one of the frames because it's an interesting way to shade and it gives a nice brick texture.
(I'm not sure if the rocks are better I just wanted to neaten them up)
If your into making games, download
Game Maker. It gives you the ability to quickly arrange mockups out of your own sprites to see how they look in conjunction with each other, and it makes games out of them as well of course
.
Great work so far! I hope you continue to expand this little world it would be very nice as an rpg.