Survival horror games over the years, all follow similar themes despite the differences in game play. There is always a player placed in a surreal situation in which they have to avoid death via various traps and/or enemies and escape. Survival Horror began back in the PSX days with Resident Evil introducing the genre to the world. The player was abandoned with other survivors in a zombie infested mansion, looking for the means to escape. The game introduced the "survive" element to horror, with ammo being extremely scarce, making the monsters extra terrifying. This also gave players the choice to conserve ammo and the choice to run away from foes or take out each enemy as they came to them, and hope they ran across extra ammo. This element further added to the feel that the player was actually trying to survive the situation and not just running through a level. The game was also heavily based around puzzle elements, with the player having to backtrack to various parts of the mansion in order to find items that would allow them to access other locations. This combined well with the survival mechanic as all enemies the player previously left alive, would have to be faced again. This spawned many other games in the genre including "Dino Crisis," "Parasite Eve," etc... All with similar game play and structure to Resident Evil.
Along side Resident Evil, one of the most terrifying games ever to grace the gaming world was born in the new glow of survival horror; Silent Hill. Silent Hill was a unique take on the survival horror genre, giving the player free control of the camera and introducing enemies so disturbed and insane, they still classify as some of the scariest enemies of all time. Silent Hill introduced psychological horror the the gaming world with its very story based game play and non-linear levels where enemies could literally pounce on you from anywhere.The game also had a feature where the player had a radio that crackled whenever an enemy was nearby. This made things extremely nerve racking when you where in an open area with fog blocking your vision from any possible threats. From these game play additions, the game took fear to a whole new level, making you scared to the point where you were paranoid of the monsters lurking in the dark so much, you didn't want to turn the corner, for fear of what means of horror awaited you. Meanwhile through all of this, the puzzle solving element still remained with the player having to solve satanic puzzles and being forced to interact with extremely creepy individuals in order to proceed.
The success of these games were mainly down to how the genre presented itself at the time and how it made the player feel as if they were actually in these situations. The hard to use "tank controls" that many survival horror titles used, made the character fairly difficult to control and made times where the player had to run past enemies or escape, very intense. Similarly, these games gave the player a large amount of immersion with players controlling and interacting with charming and believable characters throughout the story. Nowadays, some survival horror games still keep these themes, with players scavenging for ammo whilst trying to escape from their doom, most recent of which being The Evil Within; an up to date homage to early survival horror titles, most notably of which, Resident Evil.
As video games progressed and new trends were forming within the games industry, so did the survival horror genre. Game play elements began to diversify, with survival horror games starting to appear vastly different. Resident Evil 4 introduced a more shooter heavy element, focusing more on the game play and story line instead of the puzzle solving element. Despite the lack of terrifying monsters, the intense feel being overrun with very little ammo remaining still stayed, and the fact that although the terrifying monsters were rare, that made them even more terrifying. The Regenerator still haunts me to this day with its near invincibility and nightmarish breathing. This proved that survival horror could take the leap from isometric, fixed camera angles with puzzle solving features being the main feature, to over the shoulder, action infused game play, with a more in depth story line.
Most recently, the trend in these games have been "pure" survival horror, in which the player has no weapons to defend themselves, with the only item they keep throughout the game being a flashlight or other light source. These games return to the puzzle solving game play style, but with the added factor of having to sneak past and avoid enemies, with them usually being one hit kills. The game to introduce this current trend being Amnesia: The Dark Descent. This game took the psychological horror feature and took it to the next level, implementing an actual sanity meter that decreased when the player looked at the enemy for too long. This added to the scare factor as not only were you scared by first seeing an enemy, you were also dying in game.
Throughout every game in the survival horror genre, the game play structure through all of these are mostly linear due to how story based the games are and how the game has to work in order to try to scare the player. Many survival horror games work on the basis that the player triggers events in the game (usually in the form of puzzles) that set in motion events that attempt to impede or scare the player. and in order to do this, the game play has to be set in a slightly linear way. Even Silent Hill, with all its free roaming is still fairly linear, as the player has very little to do in that open space until they go to the area that has a key item or character, which will let the player progress further.
The narrative structure of the genre can be quite open, with some games allowing the player to make decisions along the game that can affect the story, with many games offering multiple endings and cut scenes. They do have the common theme of having the player character being dropped into a slowly spiralling situation that starts off fairly normal, and snowballs into something quite sinister, horrific or absolutely mad. The games in this genre tend to have a high level of immersion with the characters that you come across actually having an impact on you, especially when many games involve these characters being turned against you or violently killed.