This happened after 2045, When The Red Cross Clan created a substance that would affect the human brain, forcing it to obey them. But the substance had a side effect, people became possessed and turned into monsters that eat and destroy everything! The clan members assuming this outcome and built flying machines, but here they were not lucky... The aircraft didn't have enough power to take off and the zombies devoured them all. You can recognize them by the red cross sign on their raincoats...
Before that, you lived a normal life ,but now your task is to survive in this chaos, and do not let the zombies destroy your shelter. Defeat waves of Zombies and Bosses, buy traps and weapons, and improve your stamina. You can also change the difficulty of the game. Good luck, you will definitely need it!!!