found a little cheat buy a sniper to start ....then when you can afford the cheapest tower wait till you can upgrade it to the maximum, then upgrade to 4 stars , then when on 4 stars upgrade again but when your doing this keep pressing upgrade button as fast as you can , you will see the damage of the tower sky rocket and you now have a 5 star sniper tower [but you owe the bank the money but just for the 500 for a sniper tower ] so you have a miles cheaper [by 500]sniper...keep trying is sometimes does not work , if it dont work buy another cheap tower and try again, the trick also works for all other towers [you can upgrade without having the money if you press upgrade button really quick] but you will owe the bank the money.
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