For one of the maps, I've set the goal that the player starts near the very top of the valid grid, and the exit must be near the very bottom. All (or nearly all) the 768^2 maps had the player start at the bottom and ascend, which is a very natural progression to the point of being the default. I wanted to see what the hurdles were in designing a map where the player is always descending, deeper and deeper, without just stacking locked chambers.
http://lunaran.com/pics/lunsp2/m2editor_side.png
Discouraging shortcuts is tricky in a game without falling damage, as is creating combat scenarios where monsters below you are still threatening.
When I build it out for real it'll be fun to transition the visuals to an extreme degree as you descend, so it feels like you're disappearing into the bowels of the earth.