This Battlepad map features a subterranean chasm spanned by a wooden bridge. One side of the bridge is controlled by orcs, and the other side by Duergar. There is an uneasy peace between the two sides, supported by trade. The orcs capture humans on the surface and then sell them to dwarves who put them to work as slaves. The sheet used for the map is currently being funded on Kickstarter.
Battle Pad Kickstarter link