S.O.S: State of Survival is a free iPhone game that immerses players in a post-apocalyptic world filled with zombies. With over 100 million users globally, the game challenges players to build their base, rescue survivors, and research the zombie virus to secure their survival. Players must gather resources from the remnants of civilization while navigating threats from both zombies and other players. The game encourages strategic alliances, as cooperation is key to overcoming the infected world.

Players can create their own end-of-the-world empire by constructing a safe haven for survivors and discovering heroes with special abilities to aid in the fight against the undead. The game combines resource management, strategy, and social interaction, making it essential for players to adapt to the new rules of survival. As the game evolves, the challenges increase, providing a dynamic experience that keeps players engaged.