he objective in Days of Ruin is for the player to defeat the enemy army with their own army. Except in certain single player missions with special objectives, there are two ways to defeat an opponent: destroy all of the enemy's units or capture their headquarters. The battle system is turn-based. Two to four armies, each headed by a commanding officer (CO), take turns building and commanding units on grid-based maps. Every turn, units, which consist of ground, sea and air units, can move across the different types of terrain and attack enemy units or perform other actions, such as submerging a submarine or resupplying friendly units. Fog of War, a phenomenon that prevents players from seeing enemy units other than those in the visual range of their units, various weather conditions which change the terrain effects of the entire map, CO powers, and many other factors can affect the battle.