First-person shooters are a type of three-dimensional shooter game, featuring a first-person point of view with which the player sees the action through the eyes of the player character. They are unlike third-person shooters, in which the player can see (usually from behind) the character they are controlling. The primary design element is combat, mainly involving firearms.
First person-shooter games are also often categorized as being distinct from light gun shooters, a similar genre with a first-person perspective which use light gun peripherals, in contrast to first-person shooters which use conventional input devices for movement. Another difference is that first-person light-gun shooters like Virtua Cop often feature "on-rails" (scripted) movement, whereas first-person shooters like Doom give the player more freedom to roam.
The first-person shooter may be considered a distinct genre itself, or a type of shooter game, in turn a subgenre of the wider action game genre. Following the release of Doom in 1993, games in this style were commonly termed "Doom clones"; over time this term has largely been replaced by "first-person shooter". Wolfenstein 3D, released in 1992, the year before Doom, has been credited with introducing the genre, but critics have since identified similar though less advanced games developed as far back as 1973. There are occasional disagreements regarding the specific design elements which constitute a first-person shooter. For example, Deus Ex or BioShock may be considered as first-person shooters, but may also be considered role-playing video games as they borrow from this genre extensively. Certain puzzle games like Portal are also called first-person shooters, but lack any direct combat or shooting element, instead using the first-person perspective to help immerse players within the game to help solve puzzles. Some commentators extend the definition to include combat flight simulators where the cockpit or vehicle takes place of the hands and weapons.