Intelligence/Fallout 2

Intelligence is one of the seven primary statistics in the SPECIAL system.

Gameplay
Modifies: the number of new skill points per level, numerous dialogue options, and many skills.

Low levels of Intelligence impacts gameplay. In some cases, where a character with normal vocabulary would need to persuade them or offer a service in exchange, these characters will often give the character gifts or allow them entrance in certain areas for free out of pity.

Increasing

 * Intelligence can be raised permanently in three ways. First, by using ACE and the yellow memory module (+1). Second, by the Hubologist zeta scan/alignment in San Francisco (which can also provide +1 Luck, though the game may need save-scumming to get a bonus rather than a penalty). The last method is to take the Gain Intelligence Perk. The bonuses from these methods stack for a total of +3 Intelligence.
 * It can be increased by +1 for purposes of dialogue only, by taking the Smooth Talker perk.
 * Mentats can be used to temporarily raise Intelligence by 2.
 * Intelligence can be temporarily raised by 1 point by the Purchase the Kesting Special quest given by Miss Kitty in the Cat's Paw brothel.