The Background and Forgeround graphics of Jungle Ruins from the Genesis game called Wonderboy in Monster World.
What do you think?
There was no need to use FG2 and overwrite GFX17's graphics, as both BG2 and BG3 were free. If the user wanted to use those slots they could easily cut and paste the contents of the ExGFX into a copy of GFX17 themselves and overwrite the tiles of their choice instead.
The open door tiles in the BG Map16 (tiles 9872, 9873, 9882 and 9883) don't seem to be useful for backgrounds. In fact, they weren't used at all in your sample levels. The foreground version of them is fine though, as they're actually useful in that form for being easily placed throughout the level. On the topic of Map16 tiles, make a copy of tile AF3 (yellow stone block) that acts as a ledge, to be used together with the steep slopes and avoid "hill tripping".
Colors 1 to 7 in palettes 4 and 7 were overwritten for no reason. That's not allowed, even if you overwrite them with the vanilla colors, as the user might be using their own colors there.
Submission guidelines state: "Make sure your Map16 page screenshots are clean from clutter and junk tiles."