when playing final fortress you have to take out the opponent while guarding a power plant. Try buying heavy duty mines and placing in the middle of the green area to destroy mare tanks and trucks. Buy two to three air long-range guns and at least two short-range ground guns. Aim for the bigger tanks if you have at least two short-range guns. Those guns will destroy the small troops(they look small but they still can do big damage if you leave them alone)and the small tanks(remember to check your guns they can be destroyed). The long-range air gun shoots down the plains in level 3,4,or 5 there are a lot of plains. tip:use your money wisely you only so much but you get more every level. When at the sea coast use caution don't just buy ground and air there are going to be ships and boats that fire you there are a lot of nuclear missiles that you have to shoot. you get a lot more money but try the generator that restores health to your guns( doesn't repair you). You can only buy six short-range ground guns and four long-range air guns. Also buy water mines because between the land and air combat you don't have the full focus for the sea. The more enemy's there are try using the other generator that makes your guns more fast.