Free accounts experience certain hurdles that paying users can bypass:

: These drop starting at level 25 and are the only way to get "Black Gear." They require a

: Progressing to level 100 as a free player requires significant time investment to farm for "Nanotonium" and "Augment Cores."

: By creating a Ninja Kiwi account, you can link your progress between mobile and Steam to keep your rewards across all devices. SAS: Zombie Assault 4 on Steam