Their initial effectivenesses are determined by the primary statistics, but three can be given a 20% boost. Traits are character qualities with both a positive and negative effect; the player can pick two from a list of sixteen. During gameplay, the player can gather experience points through various actions. For gathering experience points, the player will level up and may increase their skills by a set number of points. Every three levels, the player can grant themself a special ability, or perk. There are 50 perks and each has prerequisites that must be met. For example, "Animal Friend", which prevents animals from attacking the player character, requires the player to be level nine, have an intelligence of five, and have an outdoorsman skill of 25%. Exploration and combat In Fallout, the player explores the game world from an isometric perspective and interacts with non-player characters (NPCs). Characters vary in their amount of dialogue; some say short messages, while others speak at length. Significant characters are illustrated with 3D models, known as "talking heads", during conversations. The player can barter with other characters or buy goods using bottle caps as currency. The game has companions that the player can recruit for exploration and combat, although they cannot be directly controlled. There are three main quests where completion is required, two of them given after completion of the first one. The first main quest has a time limit of 150 in-game days; the game ends if the player fails to complete it within the allotted time. Some characters give the player side quests; if the player solves them, they receive experience points. The player can use the PIPBoy 2000, a portable wearable computer that tracks these quests. Many quests feature multiple solutions; they can often be completed through diplomacy, combat, or stealth, and some allow solutions that are unconventional or contrary to the original task. Based on how they completed quests, the player can earn or lose karma points, which determine how others treat them. The player's actions dictate what future story or gameplay opportunities are available and the ending. Combat is turn based and uses an action-point system. During each turn, multiple actions may be performed by the player until they run out of action points. Different actions consume different amounts of points. The player can rapidly switch between two equipped weapons, and may acquire a diverse range of weapons, many