A type of Game System where a character's abilities are determined by the class that they choose. Most common in Role Playing Games, but recently it has begun appearing in other genres, particularly First Person Shooters. A character class is defined by the abilities that it lends to a character -- as such, two different characters of the same class are theoretically interchangeable, in that they can play the same role in the game because of their similar abilities. However, Character Class Systems have varying levels of Character Customization -- ranging from characters of a given class being literally identical to having so much variety that character class is no longer even a good indicator of that character's abilities. Character Class Systems frequently include one or more Point Build