the enviroment is really cool but the balance is quite, many things can be studied,
1) Is imposible to reach the enemy base in early times. I am not fanatic with that, but I think if you are going to block, block with a green creep only, you are blocking the 3 paths with a red creep and flying orange. The red creeps are going to agro. I know some melee guys who doesn´t like that.
2) creep selection, creeps only flyers for a goldmine is not that good idea, it means a really late expansion. Undeads and orcs have good ways skills to make them ground and raid them easy.
Undeads have the benefit to take them down with the nerubians, once the upgrade necropolis, web and go, while the humans need airborne,
And only ground creeps is not good either, after playing one of my maps I figure out that a red creeps only with melee units such berserkers can be eliminated with only one early flyer like the dwarf gyrocopter.
Sugestion: orange and red creeps, should have some anti air defense. (wolfs creeps and the red creep in the center).
3) Expanding goldmines doesn´t have much wood.
4) Cliffs there are many points where a cannon tower can be build and have advantage of distance and cliff, consider using the unbuildable tile to avoid such tower exploits.
5) Mercenay camps could be attended by modificating the orange creeps corners just a bit.
6) The enviroment is nice, but never never never, sacrifice balance for beauty, the water thing is limiting the game play a lot. For example you put a lot of cliff (orange marks). You are not going to enjoy the view because the cliff blocks the view and you are loosing a lot of space, there could go the green creeps or more wood to the map.
7) Orange creep without loot, I know people fanatic with the loot and an orange creep can´t have no loot. My sugestion, maybe with the banshee you can put other units. I figure out that the racial fit is not important, balance and level is more, for example when you design an orange creep consider melee units and distance units as support, only distance is weak and only melee is redundant. For example 2 melee units level 7 and one or two healers level 5 behind and that is suffering.
You have to take the healers first or you will loose units.
banshees are distant units and can be taken easy, for example using the tavern hero the dark Sylvanas type with silence skill. the banshee is more effective in company of melee units, so focus in use curse or attack from behind.
my sugestion is tavern in the middle and put the fountains (or the mercenary camps if you want to change) in the corners, you will improve the game play a lot with very little change
study my sugestions and decide if any of them result usefull
by the way nice story
raiting 3/5
see ya