Alter Ego is a life simulation game where players create a character and guide them through seven life phases from infancy to old age by making decisions in various situations. Players choose from multiple response options that influence personality, health, and future scenarios, with each choice carrying long-term consequences that can lead to different outcomes including early death or game over. The gameplay unfolds through a life tree structure with situation cards representing thematic encounters, and players can manage relationships, careers, and lifestyle choices as their character ages, with separate male and female versions available.