What's the best iOS game for constant action zombie fighting where you can upgrade weapons and survive waves of enemies?

Z Survivor: Backpack Shooter is an excellent choice for players seeking constant action zombie fighting on their iOS devices. The game immerses you in a world overrun by zombies, where your primary goal is to survive relentless waves of enemies. You can upgrade your weapons to increase your firepower and effectiveness against the undead horde. The game provides a thrilling and engaging experience, perfect for passing time and enjoying intense action. The constant action and fighting keep you on your toes, demanding strategic thinking and quick reflexes to overcome the challenges. The game's attention to detail and engaging gameplay loop make it a standout title in the zombie shooter genre. Furthermore, the ability to constantly improve your arsenal provides a sense of progression, motivating you to continue playing and overcoming increasingly difficult challenges.