It's funny how everyone is saying the exact same thing just with different wording.
@Accname, Yes, a melee map is considered to be a playable terrain. If you take any melee map in wc3 and remove all the creeps, shops, and gold mines, then you have a playable terrain right there. However, melee maps in WC3 are really simple and boring. You will notice that most entries will be a lot more complex and less symetrical then a melee map. So you
can make it like a melee map, but you will need to go alot more complex in your pathing layout to make the best entry possible.
And about you most recent post, sure it is allowed to have your unit walk through all doodads with no restrictions, you're not going to get disqualified if that's what you're getting at. But, honestly, why would you want to do that? You will get very low marks on the playability scoring.
Hope this helps. Good luck.
Anyways here is my first wip. Only the playable part of the terrain. Now to work on the theme by constructing epic... you'll see. Side view to see height variation and top view to view the rest.


These are already completely playable. Every platform in the pic can be stepped on and pathing blockers have been placed to avoid falling off.