Would it be possible to be able to add an option when creating maps, to allow the the Chinook to begin the mission on level 1 of the map, instead of level 0 ?
This would then allow there to be a level beneath the ground.
This would open up the game to have the maps such as Mines, Catacombs, Bunkers, Sewers, Basements and Caves modded in at a later date. Not to mention sublevels for potential Hive missions.
Another option with this would be that it would enable the chinook to land on top of a building and a mission to clear out the occupants from the top down.