In the realm of massively multiplayer online games (MMOs), there are very few based in the horror genre as of 2011. Of the horror MMOs that are available, the majority by far are in a category known as survival horror, in which players must work together to keep their characters alive in a world that is largely, if not completely, hostile. Narrative, role-playing and story-driven horror MMOs involve moving players through a storyline marked with genre-specific archetypes such as demons, vampires and graveyards. Horror MMOs sometimes involve standard types of MMO gameplay, such as player-versus-player combat, but use horror-related models for characters or have backgrounds that evoke classic horror environments.
Survival horror MMOs basically place players in a world where most of the computer-controlled characters are actively hostile and, sometimes, actively hunting the players. These games normally are combat-based and have some type of resource management that keeps the players moving, such as having to find ammunition for weapons or food to keep a character from dying. Although zombies are a popular adversary in such games, nearly anything from generic monsters to robots can be used as enemies. Players work together in survival horror MMOs to reach resources and safe areas and to defeat hordes of enemies that a single player would not be able to defeat alone.
Narrative-style horror MMOs create tension, suspense and surprise through storylines and plots. These can be revealed through exploration, combat or puzzles. The narrative structure lends itself more toward social interaction, with players becoming involved in the story and potentially role playing. One drawback with this type of horror MMO, however, is that there is no re-playability once a storyline is complete, meaning the players might exhaust all of the game content before the developers can release more.
Horror MMOs can be exceedingly difficult to create and occasionally may have their status as a horror game questioned. Sometimes, this is because offline, single-player horror games often rely on the solitary nature of the player, character and the gameplay to create scenes or environments in which there is a certain amount of control or scripting. This control allows the designers of a horror game to maintain an atmosphere of fear and uncertainty and develop other elements that define the genre. Within horror MMOs, where hundreds of players are all talking and playing together simultaneously, there is little control of the atmosphere, removing the sense of isolation or tension present in offline horror games.