In the year 2032, aliens have invaded Earth. Humanity bands together and fights back valiantly, but they are simply no match for the invading force, and their numbers steadily dwindle as fighting continues. At the brink of extinction after years of war, one last hope for humanity appears: Black Rock Shooter, a young girl who is also the most powerful biological weapon ever created. Working together with the last remnants of the human race, will she be able to repel the alien invasion and save the Earth?
Black Rock Shooter is an action-RPG based on the anime of the same name. It is in many ways a standard Japanese-style RPG. The player controls the eponymous Black Rock Shooter as she explores the battle-ravaged landscape, and enemies will approach her when they notice her. If they get close enough, the game will switch to battle mode, which is closer to a rail shooter rather than a standard turn-based battle system.
During battle, enemies will attack in real time. The player controls a cursor to aim Black Rock's rock cannon, and can shoot freely, as well as block, dodge, and use various items and special skills, but she cannot move freely around the battlefield. Certain actions will increase a heat gauge, which will only lower if she is allowed to rest. If the gauge gets too high, she will become temporarily unable to attack.
The game is divided into stages, each of which contains a number of missions and optional objectives. The stage ends when these missions are cleared. Optional objectives in each stage will reward the player with additional abilities and unlockable bonuses such as weapons, costumes, and concept art. Completed stages can be returned to in order to complete additional objectives.