It’s often assumed in IF — but not always the case — that the protagonist of the story is also the viewpoint character and the person whose actions are controlled by the player. Those interested in studying player character may also be interested in past rec.arts.int-fiction discussions .
Disruptions of the Triangle
Protagonist/narrator/actor split. The usual protagonist-narrator-actor equivalency is not in force in these games.
Multiple protagonists or viewpoint characters. Your point of view shifts between several different player characters over the course of the game.
Unreliable narrators. Some narrators suffer from perception-altering diseases or otherwise aren’t being straightforward with the player. In a few cases, they just don’t have the intelligence or social context to view things in the same way the player would, so their descriptions take a little decryption. (Just reading these lists may be a bit of a spoiler for the games in question, so be forewarned.)
Strong narrative voice. A lot of IF protagonists are vaguely sketched or customizable in order to allow the player to project themselves into the role, but some go the other direction and present a world that is strongly flavored by the attitudes of the viewpoint character.
Customizable protagonists. The player is allowed to adjust aspects of the player character (often explicitly, at the beginning of the game). This feature is an especially strong brand identifier of the Choice of Games line: most of these works let the player select gender, sexuality, and an assortment of personality traits during the first portion of play.
Non-human protagonists. Non-human protagonists are fairly common from early commercial IF onwards. These include fantasy races such as trolls, orcs, hobbits, and elves; animals, especially cats and dogs; constructs such as robots and AI; and even inanimate objects.
Antiheroes. Not all protagonists are good; here are some games where you play the villain.