Immersive sims are primarily concerned with making players feel as though they are truly experiencing a believable world by creating mechanics that feel appropriate and logical within the game world and try to avoid feeling arbitrarily 'Gamey'.
This school of game design is often associated with Looking Glass Studios, which developed Ultima Underworld (1992), System Shock (1993) and Thief (1998). The term "immersive sim" was coined by Warren Spector in his post-portem of Deus Ex (2000).
While associated with Looking Glass, there have been immersive sims predating the studio, as early as Yuji Horii's Portopia Serial Murder Case (1983). The concept of immersive sims is still alive today in games such as BioShock (2007), Deus Ex: Human Revolution (2011), and Dishonored (2012).
It should be noted that not all of these characteristics are necessarily required for games to fall into this category
- Immersion in an elaborate and believable game world.
- Simulation: physics and AI are used to create believable behavior in objects and characters which the player can freely interact with, resulting in 'emergent gameplay'.
- First-person perspective so as to truly look through the eyes of the protagonist.
- Game design that allows for multiple paths and/or multiple solutions in every situation.
- A systemic game world that keeps track of the player's actions, which can affect the "whole" game.
- Open-ended/non-linear game design with an emphasis on choice and consequence.
- Full control over the player's character in every situation.
- A world with consistent rules that the player can interact with.
- Narrative that is not always forced on the player, but instead can be told through exploration and gameplay at that players will.
- No fail states, beyond player death.
Rock Paper Shotgun ran a series of interviews on the past and future of the genre and the GAMBIT Game Lab also interviewed several ex-Looking Glass developers on the subject.
Many of the core elements of immersive sims predate Looking Glass Studios. Many of these elements are found as early as Yuji Horii's 1983 adventure game Portopia Serial Murder Case, which can be considered the first immersive sim. It was a first-person adventure game with an open world, character AI, choices and consequences, non-linear game design, open-ended narrative told through notes and diaries, interactive environments, emergent gameplay, allowed multiple ways to achieve objectives, and lacked fail states.
Immersive sim elements also appear in varying degrees in the adventure games Takeshi's Challenge (1986) and Snatcher (1988), the action-adventure Legend of Zelda (1986), the first-person role-playing shooter Star Cruiser (1988), the Zelda-inspired action role-player Times of Lore (1988), the survival horror role-player Sweet Home (1989), and the stealth game Metal Gear 2: Solid Snake (1990). The direct predecessor to Looking Glass Studio's immersive sims was the role-player Ultima VI (1990), which was in turn influenced by Times of Lore and Legend of Zelda.
While many of the core elements of immersive sims predate it, the game often credited with establishing the immersive sim school of game design was 1992 role-playing game Ultima Underworld, produced by Warren Spector. It had nearly all of the defining elements mentioned above, and became a general template for later immersive sims. It was influenced by Ultima VI, which was in turn influenced by Times of Lore and Legend of Zelda.
Immersive sims generally tend to overlap with genres such as stealth, survival horror, first-person shooters and role-playing games. The Thief and Deus Ex series, for example, heavily incorporate stealth elements. Warren Spector's Deus Ex series was also inspired by first-person shooters such as GoldenEye 007 as well as role-playing games such as Suikoden. Immersive sims such as System Shock 2 and the BioShock series also heavily incorporate survival horror elements.