 Characters do not level up in a way similar to standard role @-@ playing games ; instead , stats evolve according to two <unk> systems . The " Self Evolution System " alters stats and skills depending on their usage during battle : for instance , a repeated use of left @-@ handed attacks increases the character 's left arm strength , while running around often increases their speed . The second system is the " Code Extension " mode , in which Code Points can be spent on either of the two arms or up to four body slots to increase their stats or acquire new skills . Code Points are earned after each mission in amounts that depend on the quantity of " Dropped Code " collected from defeated enemies , as well as mission clear time , and damage done and taken . When replaying completed stages , the amount of Code Points earned is the difference between the player 's highest past score for the mission and the new score obtained . 
