its an easter egg, kinda live started to range from 0-9-A-F because theres not enough space to write 100 down. and when the lives started to become random letters, thats just how infinite lives look like
well, your username sure does say a lot 'bout ya ok so you copy & paste the characters folder (mario for example) in to skins folder, rename it to whatever you want and then start changing sprites, change the player.txt file to change some stuff (like speed of animations or adding/removing frames)
