Princess diep of the diep kingdom is kidnapped by Masse. Then a tank called Harambe sets out to find her.
Harambe's 1st stop is Piggy Island
You start as a lvl 1 tank. You just need to kill a tank with the same level (lvl 1). Very easy fight. After that's finished, you get 1 upgrade point.
Same, but you need to deal with 2 of them.
Same, but you fight 3 of them
You need to deal with the elite tank. He awards you to a lv 7.5.