Valiant Hearts is a puzzle-based game which takes place across the course of The Great War, putting players in the role of four characters; the Frenchman Emile, his German son-in-law Karl, American soldier Freddie, and Belgian nurse Anna.
The game comprises four chapters split into several sections, with each section requiring the player to clear an objective in order to progress through the story, most of which generally involve solving puzzles by obtaining certain items needed for the situation. Other sections include wartime segments requiring the player to survive heavy gunfire, stealth sections where the player must avoid being detected by enemies, and rhythmic car chase sections set to classic songs. Each character is able to interact with objects, perform a melee attack to knock out guards or smash through debris, and aim and throw projectile objects such as bricks or grenades. There are also some traits unique to each character. Emile has a shovel which lets him dig through soft ground, Freddie carries shears which can be used to cut through barbed wire, and Anna is able to treat patients for injuries, which requires the player to press buttons with precise timing.