In the near future, robot technology is ubiquitous across the world. Unexpectedly, robots across the United States begin to go haywire and attack anyone and everything, leaving the humanoid Beck and Call as the only bots still functioning properly. Beck is a combat robot and the latest in the Mighty Numbers line, and the only among them able to manipulate Xels, the nanomachines that all robots are comprised of. Thus, he is asked by his creator, Dr. White, to bring the other Mighty Numbers back to their senses and discover the source of the robot affliction.
Gameplay is heavily inspired by the Mega Man series, and consists of running and gunning across platform levels while defeating enemies along the way. Beck's basic weapon is fairly weak, but once he has sufficiently damaged an enemy, he can dash into them to instantly defeat them and absorb their Xels. Each enemy has a different type of Xel, which can grant Beck temporary power-ups such as healing or increased defense. After defeating another Mighty Number in a boss battle, Beck may also use their unique Xels to transform and gain new weaponry. Call is also available in co-op play; while she cannot absorb Xels, she falls slower, dashes farther, and has a shield that absorbs projectiles.