The Pip-Boy 3000, shown displaying the player's current skill ratings.

The game begins with the main character as a newborn, whereupon the player determines the race, the gender, and the general appearance of their character. As a one year-old baby, the infant reads a child's book titled You're SPECIAL, where the player can set the character's starting S.P.E.C.I.A.L. primary attributes: Strength, Perception, Endurance, Charisma, Intelligence, Agility, and Luck. The character gains a set of Skills with base levels determined by these attributes. At age 16, the player takes the Generalized Occupational Aptitude Test (G.O.A.T.) to determine the three Skills they wish the character to focus on.[10]

As the character progresses through the game, experience points are earned that are used to achieve levels of accomplishment. Upon achieving a new level, the player receives a set of skill points that can be assigned to improve any of the Skill percentages. For instance, increasing the lock pick skill grants the player the ability to pick harder locks to unlock doors and supply crates. A Perk is granted at each level, which offers advantages of varying quality and form. Many Perks have a set of prerequisites that must be satisfied, and new Perks are unlocked every two levels.[10]

An important statistic tracked in the game is karma. Each character has an aggregate amount of karma that can be affected by the decisions and actions made in the game. Positive karmic actions include freeing captives and helping others. Negative karmic actions include killing good characters and stealing. Beyond acting as flavor for the game's events, karma can have tangible effects to the player, primarily affecting the game's ending. Other effects include altered dialogue with non-player characters (NPCs), or unique reactions from other characters. Actions vary in the level of karma change they cause; thus, pickpocketing produces less negative karma than the killing of a good character. However, the player's relationships with the game's factions are distinct, so any two groups or settlements may view the player in contrasting ways, depending on the player's conduct. Some Perks require specific karma levels.[11]