[Aezeal]

Well the whole idea isn't balanced in anyway since non air, non astral nations would have a very hard time competing.

PS you should look up one of my maps, not the most beautifull but it has caves, land and then cloud regions lots of bottle necks ect

http://forum.shrapnelgames.com/showthread.php?t=36053 --> this is it

you could also make the regions owned by AI controlled thingies which start with advantages (modded in the map file) In my gangwars map (see below) I've also found out a way to make another nation take place in a bottleneck (between you and the AI's that start more powerfull) and then make that AI do nothing (I think it acutally isn't AI anymore but still a separate nation, I really can't remember how I did that but it should bereproducable) but still have it allied with the AI nations so they don't break out.

Makes it so you can fight for the "material" plane and then if you want you could attack the AI which blocks the real AI's and force your way into the outer realms by attacking (for example) an elemental temple with the acces to one of the planes.

In my map there was room for 4 players , they where put 2 together, they seperated by a powerfull indie province and then agian 2 together.. so you have an enemy to start with.
They if you want to moce to the inner city (ti's a city map) you could attack at the gates (where the inactive AI is) within the gates there where 2 AI's that started off more powerfull, but htey could attack eachother and then later another gate to the castle where the King (and his nations) started, not much land but a lot of bonusses there.

Try the map and see the options you could use.