Saaay, I gotta admit that this looks pretty good! :D
The story is essentially out of the mold, and still sounds interesting; the screenshots, you managed to pull off the D/P look quite well. If you want new tiles, I (and it's in italics because many disagree) recommend HGSS tiles. Try hunting in the Resources section, you should probably find compilations of the tilesets there; you could also try deviantArt and other such websites.
At any rate, good luck with this! :D