The idea is great, but I think it's time for some model editing on structures:
I suggest this model for a scout tower, which has upgradeable Sight (Max upgrade reviews the whole map for team): http://www.hiveworks...t-tower-233550/
Level 2 Mine: http://www.hiveworks...0&d=list&page=5
Level 3A mine (Faster gold gather):
http://www.hiveworks...0&d=list&page=3
Level 3B mine (Larger gold income):
http://www.hiveworks...0&d=list&page=3
(You can only upgrade to one of those)
Level 6 Lumber mill (max. Wood & Faster Income - can't be upgraded after that to Mine): http://www.hiveworks...0&d=list&page=3
New Barracks model ( or maybe new level ) - http://www.hiveworks...0&d=list&page=7
Max. Tesla tower: http://www.hiveworks...0&d=list&page=7
Max. Flamethrower tower: http://www.hiveworks...0&d=list&page=6
Now you can build multiple Command Centers, but only 1 can be upgraded to HQ ( which allows you to some special tower & wall upgrades, also leveled ) - http://www.hiveworks...0&d=list&page=3
Nuclear plant - now with Nuke made from mana!
http://www.hiveworks...&d=list&page=21
Upgraded Factory (Repair):
http://www.hiveworks...&d=list&page=21
(V Alternative version V)
http://www.hiveworks...0&d=list&page=7
Technology research (Tower & Wall HP, Attack, Retaliation, regenartion, etc.) http://www.hiveworks...0&d=list&page=3
(V Alternative version V)
http://www.hiveworks...0&d=list&page=7
New Command Center model: http://www.hiveworks...&d=list&page=15
Missile tower: http://www.hiveworks...&d=list&page=16
Bunker: http://www.hiveworks...&d=list&page=15
Max. Arrow tower: http://www.hiveworks...&d=list&page=13
And a new boss, Dark Shadow: http://www.hiveworks...0&d=list&page=4
New boss: Hellios Terminatus: http://www.hiveworks...emental-232884/
& why a hell-defence map don't have a Devil? :http://www.hiveworks...0&d=list&page=4