I just get my fully upgraded mortar teams and repeatedly fire airstrikes on the robots... it was actaully one of the most easy levels for me. Just upgrade nothing but gunners and use nothing but gunners until you get mortars. Then just upgrade nothing but mortars and get nothing but mortars... maybe on that level where you get 8 units to choose i would get 4 Gunners in the corners and 4 Mortars.
normally the snipers were key to me...I mean they dominated everything because I could use alot of them at a time...then here comes the last level and i have to defend 8 spots with 3 guys....I have the mortar guys fully upgraded as is every unit ( except telsa there useless ) but the mortar guys take WAY too long to fire and i end up getting killed.
