The game is set in the world after the spread of fungi. Players play the role of a fortress city to resist the attack of various infectious agents and mutants. First of all, we need to upgrade the buildings in the fortress. On this basis, we can build turrets on the bases outside the city and on the walls, and produce airplanes and vehicles to resist the enemy's attack. There are many kinds of turrets, vehicles and aircraft to choose from in the game. There are differences in blood volume, attack power, and money needed for construction and upgrading. Making use of these differences to develop tactics and repel the enemy is the core of the game. In addition, there are differences between each simulation scene in the game, and the tactics in each scene also need to be adjusted.