Black Rock Shooter: The Game is an action role-playing game and based on the Black Rock Shooter franchise created by Huke. The players take on the role of the eponymous Black Rock Shooter. The game is divided into several missions in which the player must clear objectives to progress. On the main overworld, BRS can explore the available areas and look for certain items. Battles begin when the player comes into contact with an enemy on the overworld. During a battle, BRS can aim and shoot with her rock cannon at enemies, block against attacks, and sidestep to avoid them completely. If the player fires the rock cannon or uses the sidestep too much in a short time, the system will overheat, leaving the player vulnerable to attack until it cools down. Throughout the game, players can earn abilities that can be equipped to BRS and used in battle, each with their own cooldown periods. These include offensive attacks such as a powerful blast, a sniper rifle, or support abilities that can increase BRS' stats such as her attack or defense. Certain sections will also see BRS ride a motorcycle, in which she can attack enemies on either side of her or use weapons to fire in front of enemies.

In the year 2032, Earth suffers from a sudden invasion by alien forces. Nineteen years passed after that event, and with chaos ruling the globe, the only way to rescue the world from utter destruction is to survive and fight against those who force Earth into complete annihilation.

The main character of the game, Black★Rock Shooter (portrayed in the game as a "living weapon" designated with the name BRS), is entrusted with the responsibility to protect mankind, possessing the ability to fight against the invaders as the ultimate weapon. She emerges from the ruins of San Francisco and witnesses an amassing of surviving troops which becomes her support throughout her mission.