An archetype is also a term used in role playing games, both the game type and the traditional pencil-and-paper type.
The character classes in Dungeons and Dragons are an example of this concept. Each class the player can choose to begin with represents one typical type of adventurer - the tough and skilled fighter, the nature respecting druid and the sneaky rogue or thief are examples of character archetypes. While there can be a great deal of variety within any one character class - for example, the wizard can be a fireball wielding battle mage, a wise and knowledgeable sage or a heartless evil necromancer - the character classes help to simplify a character's choice and direct their adventuring career by giving the character a basic model or framework to build their character around.
It allows a player to directly compare their character to others of their type, as well as giving the DM a way of estimating the characters' current power relative to the challenges they should be set. It gives each player in the group a feeling that they have their own role in the group, each fulfilling a certain niche better than the other players and relying on the other players to support them by fulfilling theirs. This, in turn, gives them a sense of accomplishment when they are the only one in the party able to bring a fallen ally back to life, disarm the trap and pick the lock on an ancient vault or decapitate a dragon with one swing of a sword.
Dungeons and Dragons Third Edition takes this further, with the addition of prestige classes - extra classes which an existing character may multiclass into to gain certain new abilities. This too is designed to give a player a certain archetype by specialising their role even further. A tough dwarven fighter may take the Dwarven Defender prestige class, further defining his character as the tough fighter type, or an evil rogue (thief) might take up the Assassin prestige class if that represents the career path he is taking.
In some video game RPGs, such as the Realms of Arkania trilogy, the term "archetype" is used as a synonym for "character class". The reason for this is that to avoid seeming too much like another game or RPG system that inspired it, games and RPG systems often invent their own terms for everything. Lone Wolf uses Combat Skill and Endurance, for example, while D&D uses terms such as Base Attack Bonus and Hit Points, and another roleplaying book I read as a kid named these Strength and Wounds.