The survival horror genre is unique from other video game genres in that it is not generally defined by mechanics, but rather by theme, subject matter, and design ethic. Survival horror games are rooted in the conventions of horror fiction and they focus on surviving and escaping a dangerous scenario rather than rescues or heroics. They generally depict protagonists that are relatively ordinary and very constrained resources such as health and ammunition. They most commonly feature action game and/or adventure game elements, usually a combination of both.
Survival horror games use puzzle solving and exploration as routes of progression through the game. The player often must contend with limited supplies such as ammunition and health; hence "survival" horror. The player character is often portrayed as being unfamiliar with the setting in which the game takes place, contributing to the feeling of isolation and discomfort. Some games provide 'safe' rooms or areas, where characters can heal, consult a map or save the game without fear of attack. In some games, even these areas can become dangerous, allowing no respite. Survival horror games are also infamous for having several enemies who are capable of killing the player in just one attack.
Most survival horror games are single player only, though a few exceptions have appeared. Players are typically armed, but rarely as well-armed as characters in other genres such as first-person shooters. Makeshift weapons such as metal pipes, kitchen knives and other improvised weaponry are often used. The player's most preeminent goal is generally to escape from an isolated area that is overrun by enemies, which can be defeated in combat, though avoiding enemies is often preferred or even necessary in order for the player to progress.
Game developers use several techniques to unsettle the player and make him/her feel underpowered, with the strength or number of enemies reflecting how well-prepared a player character is. If players control an 'average Joe' type character wielding a makeshift weapon, that character seems more vulnerable, allowing even human-sized enemies in small numbers to threaten the player. Should the player be controlling a soldier armed with firearms, then the enemies will be made larger, more powerful and appear in greater numbers in order to achieve the same effect. Many survival horror games feature protagonists or related characters who are stereotypical weak females (for example the Fatal Frame series); again this is often the developer trying to make the player feel under-prepared to face countless antagonists. However, experienced women are also portrayed. The Resident Evil series portrays brave and experienced young women, including a police officer, as part of the cast of protagonists.
Storylines in survival horror games are often not revealed directly but rather released in fragments throughout the gameplay, leaving it up to the player to put much of it together. Many have open and/or inconclusive endings with several unanswered questions via the player character's often limited understanding of the situation. It is not unusual in the survival horror genre to have several possible endings, the one given governed by the players choice of action at key points in the game.
The term "survival horror" was first used by Resident Evil, published in 1996. The original Japanese version of Resident Evil was marketed under the previously non-existent survival horror genre on the game's cover. A line of text also displayed the phrase "Enter the world of survival horror..." while the game was loading. Sweet Home in particular served as inspiration for Shinji Mikami to create Resident Evil.
Some common elements of survival horror games can be found in the 1981 Atari 2600 game Haunted House, which has been considered by some to be the earliest example of the genre, as well as in Infernal Runner, released by Loriciel in 1985 for the Commodore 64 and later on for the Amstrad CPC.
Clock Tower and Silent Hill created a group of survival horror games that focus on psychological horror rather than just violence and shock tactics. This category deemphasizes combat in order to increase the vulnerability of the protagonist and build suspense. Similar titles include the Fatal Frame series and Siren.