Custom Robo takes place in a collect-customize-and-battle style role-playing video game genre similar to games such as Robotrek or Front Mission, but with frantic action battles in confined 3D arenas (2D arenas in Custom Robo GX), similar to Virtual On. In each game’s story mode, players slip into the role of a nameable young boy who has just had a dream about Custom Robos. After waking up, he walks up to his parents while they talk, and proceed to give him his first Custom Robo and some parts for battling. A friend then comes by to take the protagonist to where Custom Robo events are held. In each game, the first Custom Robo players obtain is always a model of the Ray series. The goal for players is to improve their skills and collect different Custom Robos in order to defeat everyone, including champion Custom Robo users.