How to win against bigger level
1.buy a 2 - 3 ninjas
2.level the first ninja until black belt & upgrade the weapon shop to buy more weapons
3.do it at the second ninja
4.then the 3rd ninja
5.If you have 3 full level up,upgrade the blimp
6.buy more ninjas
7.keep doing the 2nd to 6th steps
8.enjoy