Level up the survivors to kill all the zombies and enemies

I want to level up all the survivors every time I get a new one because it will help me to kill all the zombies immediately which will benefit some gifts and coins.

This game is really fun so I suggested this to my friend since both of us love zombie games, and she got addicted to the game because she wants to know the ending of the story of this game.

I’m glad I have discovered this game.