You should be able to dig under the map, eg.) tunnels. This would bring some new interesting dimensions to the game, Rather than when something is shot the map doesnt go over vertical
Better than everyone:9-9---------0---0---0-------9-9-0---0---9-9---0-----9--------------------------------c-c-----1---1---1---1---1-------1---1---------1--------------------------------------a-a-0---0---0---0---1---1---1---1---0---1---9-0---9----------------------------------
MEan Song 9-9---------3---3---9-------0---0-------9--------------------------------------------c-c-----2---2---2-------1---1---1-------c--------------------------------------------a-a-1---1---1---1---0---0---0---0---1---a--------------------------------------------