(Insert Rating analysis here)
Screenshots looked good, although the terrain was plain. Hey, that rhymed :p. Anyway, the way to make terrains more interesting mix different types together. Use size 1 brush mix Grass A, Grass B, and all the other grasses together. Do the same for snow and sand.
Next, trees. You can mix similar trees together like oak and pine, savanah and palm, and pine with pine snow for snow.
Don't make rivers straight, make them naturelike. When I looked at the river I was thinking you should put some lilly pads and perhaps some fish.
Rocks make the scene naturelike and good looking. Make a cluster of big rocks and some small rocks and sprites near it. Also, feel free to add some rocks freely to make the enviornment look good.
Additional Comments: I'm looking forward to the scenario, Swift sword.