Five pillars of Immersive Sims

Maxim S
14 min readMay 24, 2018

So called immersive simulation games have been around for decades, but people have different opinions about what they are and what are their core aspects and elements. What qualifies as an immersive sim? Why such different games as BioShock, Deus Ex and Thief all are considered immersive sim classics, while some other games (for example, Far Cry) usually are not?

Immersive sim is not a genre, but rather a design direction and a set of guidelines — they have been single-handedly created by the now-defunct company called Looking Glass, and there could be different schools of thought about whether games that are made neither by Looking Glass nor by any of their followers (Ion Storm, Irrational Games, Arkane Studios, OtherSide Entertainment and, to an extent, Eidos Montreal) can be considered “proper” and “true” immersive sims. In the scope of this article, however, it’s not important. The goal of this text is to classify certain games that are widely agreed to belong to the immersive simulation design, rather then to debate if certain games do or do not belong to it.

In my view, each immersive simulator stands on five pillars listed below:

  1. Choices: It is designed from the ground up to provide the players vastly different ways of overcoming challenges and completing objectives — through non-linearity of environments, significant and gameplay-defining differences in character progression, or both.
  2. Tools: It provides multitude of meaningful tools players can use, primarily through interactivity of the game world and advanced physics-based systems, that further personalize gameplay experience and self-expression.
  3. Systems: It is designed to be an interplay of many complex systems, such as AI, physics, level design and more, which result in emergent and sometimes hardly predictable gameplay situations, and ensure that each playthrough is unique to an extent.
  4. Focused Design: It usually puts players in believable, meticulously designed locations which make sense as actual places, rather than video game levels; it also puts great emphasis on production values and design aspects that matter for creating highly atmospheric, highly immersive experiences. By virtue of being “an inch wide and a mile deep”*, it constrains game spaces to relatively smaller areas, but full of rich simulation.
  5. Message: It employs mature storytelling and conveys certain ideas and messages through advanced narrative mechanisms without limiting interaction and taking control from players, and sometimes leaves narrative and dramatical choices and consequences to players.

It’s pretty clear that if you unpack the term “immersive simulator” and try to provide additional context to each of these two words, Focused Design and Message would constitute the immersive part, whereas Choices, Tools, and Systems are core to simulation.

Now, getting back to the initial question — how come such different games as BioShock, Deus Ex and Thief all belong to the same design school?

Looking Glass made a lot of great games, including Terra Nova: Strike Force Centauri and Flight Unlimited series, but perhaps three the most adored franchises by the studio are Ultima Underworld, System Shock, and Thief. These three are considered the pillars of original immersive simulation design, and interestingly enough, each of them can be put at very different spots on the immersive sims spectrum:

Games from all three of these series are very different, but they share all of the five key ingredients of immersive sims I listed above. When it comes to game mechanics, though, the main differences lie within the Choices aspect.


In stealth focused immersive sims, and Thief in particular, a defining aspect of player choice is extremely non-linear and open level design and the fact that players can complete missions by freely navigating through space and choosing their own ways. Sure, there are linear fragments to certain Thief’s missions, but most of the time levels are very open — for example, in Thief 2’s “First City Bank & Trust” there are many ways to get inside the bank building, and the sprawling level can be explored freely. Non-linearity and lots of alternative ways through spaces are inherent to the core concept of stealth gameplay — if you can’t bypass a guard undetected, find another way, and hence there should be multiple ways through almost any location.

Below is an example of a map of a typical Thief mission. This very open approach to level design in immersive sims has been later adopted by other either stealth focused, or hybrid games in this school of design, such as Deus Ex and Dishonored.

An example of a Thief mission map

By contrast, System Shock 2’s levels are quite linear. That doesn’t mean that players are on rails, like in classic Call of Duty games — the areas in System Shock 2 are very complex and require a lot of exploration and back-and-forth movement, as you can see from the map below. System Shock and similar games usually have “hubs” which connect various parts of the level and provide better narrative context. However, unlike Thief, System Shock level design is primarily about going from point A to point B with minimal to no deviations and alternative ways. Since System Shock is not a stealth focused immersive sim, there is no reason for level designers to provide paths for players to avoid certain enemies, as the core of the game is about fighting these enemies, but in various ways.

An example of a System Shock level

The same approach to level design was adopted by subsequent assault focused immersive sims, most notably BioShock games, and Prey. Even in more recent Deus Ex games by Eidos Montreal, missions are usually built as spaces for more linear progression from point A to point B.

Overall, the differences in stealth focused vs assault focused immersive sims level design can be explained by the following sketch:

In stealth focused immersive sims, there are multiple ways from Point A to Point B. In assault focused immersive sims, there is usually one way.

As mentioned above, assault focused immersive sims do not require multiple ways through each space, as the players are not asked to avoid confrontation — quite the contrary, in fact, they are encouraged to confront enemies. And while each playthrough would mean that players would fight the same enemies in mostly similar cadence, the choice is provided through player progression. In System Shock 2, players can invest in different abilities, across melee combat and traditional weapons, through Psionic skills that would allow players to lift and move objects from the distance, set up traps, hack turrets etc — which would provide lots of meaningful choices.

These mechanics have been developed further in BioShock games, where players are constantly required to experiment and choose between different vigors (or plasmids), weapons, and ammo types. Combined with interactive environmental elements players can use to their advantage in combat, such as pools of water and oil, and further enhanced by gear in BioShock Infinite, all these result in vastly different tactics and combat experiences. A sophisticated player progression system is used in Prey, and in hybrid immersive sims such as Deus Ex and Dishonored games.

Stealth focused immersive sims, on the other hand, usually do not have these complex character progression systems. In Thief 1 and 2, there is no character progression at all (Garrett in the beginning of the game can do everything he can do at the end), whereas in non-Looking Glass sequels such as Thief: Deadly Shadows and Thief (2014), the progression is somewhat rudimentary and doesn’t significantly change the play style and tactics.

Interestingly enough, the very first immersive sim in history, and the first Looking Glass game, Ultima Underworld, was essentially a hybrid approach. Underworld is neither assault focused (certainly not to an extent of System Shock), nor stealth focused (nowhere near Thief), but it combines both assault and stealth, and adds rudimentary social interactions to it. Underworld has both the character progression system (similar to very old-fashioned RPGs) and non-linear environments. It’s interesting how Looking Glass, having started at the center of the spectrum, then moved on to explore assault extreme with System Shock first, and then stealth extreme with Thief, thus developing all three key approaches to immersive sim game design.

Hybrid approach was later adopted by Ion Storm with their landmark Deus Ex. Dishonored series is another example of a hybrid immersive sim. In both these game series, players can complete objectives by both applying deep character progression mechanisms (skills, biomods and augmentations in Deus Ex, powers and bone charms in Dishonored) and choosing their paths through very open and non-linear environments. However, one can argue that action play in Deus Ex and Dishonored is inherently inferior to more fine-tuned action mechanics and character progression systems in System Shock, BioShock and Prey, whereas stealth in Thief is way more complex and granular compared to hybrid immersive sims.


Immersive sims always give players a vast array of tools that they can use to further tailor gameplay to their play style and overcome both predesigned and emergent situations. The most obvious examples are types of weapons and items players can find or purchase in the game world, carry around and interact with or use at any given time. In System Shock or Deus Ex, these are all types of items and weapons, including various ammunition, that players can carry in their inventory and interact in the game world. In Thief and Dishonored, these are different types of arrows and bolts, as well as the wide array of bombs, mines, grenades and other types of items that can help players to either combat enemies, distract, or avoid them.

Sometimes tools go hand in hand with the elements of character progression. For example, in Dishonored, players can unlock the new types of upgrades or items that would be available for purchase from merchants as they progress through the game.

In addition to a very long list of items available to players, immersive sims always provide very creative ways of exploiting these tools due to advanced physics-based mechanics. In Thief, water arrows can be shot at torches or fireplaces to create shadows to hide in, whereas rope arrows can be used against wooden or other soft types of surfaces to crate additional ways of moving through levels. In System Shock 2, levitation can be used to move objects from distance and thus solve puzzles. In BioShock, lighting cast at the pool of water would electrocute everyone in it. In Dishonored, sticky grenades can be attached to hounds or rats. In Prey, Gloo cannon can be used to create multiple new ways through space, or creatively fight or avoid enemies.

Combinations of various abilities and weapons in BioShock generate different combat tactics


Immersive sims are about multiple complex systems working together to provide unique player experience. Some of these systems are active — for example, players have choices of how they want to develop characters, progress through spaces, and which tools to use. Some of them are passive — such as interplay of AI reactions. For example, in Thief or Dishonored, patrol routes of guards are designed in such a way that at each given moment, the layout of placement of certain guards on a level can be unique, and no matter how many times players completed a mission, patience and exploration are required to sneak through a location each time. This can be further enhanced by random or semi-random patrol routes, or a guard can suddenly look up and see the player hiding up on a balcony, or wander off a regular path and discover an unconscious body hidden in a dark corner, which would result in alarm setting off.

Dishonored is a shining example of this interplay of systems — in addition to AI bahaviors mentioned above, the game reacts to how many people players kill and how they tackle certain gameplay situations, and then changes the state of the game world via the chaos system — players focused on assault and lethal approach would have to face more rats, bloodflies and guards, whereas stealthy gameplay results in the opposite. Various bone charms, which have random attributes on each playthrough, can significantly affect moment to moment gameplay — for instance, a certain bone charm can prevent hounds from smelling the player, which could result in a different stealth experience. Chipsets properties in Prey are similarly randomised. In System Shock 2, enemies respawn and carry a random set of inventory items, which could include rare ammunition for guns, that in turn can be used to overcome otherwise difficult combat situations. In Thief, a mine set off near an explosive barrel might not only cause a chain reaction of explosions that would damage player and other characters, but would also result in tremendous noise which will attract AI to a player’s position — or from a player’s position, if used smartly. It could also destroy a nearby wooden door, otherwise locked. An unconscious body of a person, accidentally dropped in water, would result in drowning. In Arx Fatalis, a piece of cheese can be dropped on the floor to attract rats, and mushrooms that heal players can grow quicker in warm environments.

Combined with many ways of addressing unexpected and unscripted events, these systems generate lots of emergent situations that make sure that each playthrough provides different experience.

When a player fails to stay undetected in Thief, running away from guards and improvisation is the best option

Focused Design

Immersive sims all take place in locations that make sense as actual “real” places, rather than nonsensical game levels — this was especially evident when Ultima Underworld and System Shock were released in early 90s, featuring logical and narratively rich spaces, in contrast to mostly nonsensical and abstract levels of the first person shooters of the time. In traditional first person single player games, levels are primarily designed to provide players with certain predetermined gameplay situations, whereas in immersive sims, they are also designed to be believable spaces. Aramis Stilton’s manor from Dishonored 2, Sheriff Truart’s Estate from Thief 2: The Metal Age or Dvali Theater from Deus Ex: Mankind Divided could easily exist in the real world — they all have kitchen rooms, bedrooms, guest halls and restrooms, many of which could be completely missed while playing the game, as they exist in the levels in order for them to be believable, rather then for certain gameplay purposes. Decks of UNN Rickenbacker and Von Braun from System Shock 2 and interiors of Talos I from Prey are similarly designed to make sense as (once) inhabited spaces. Even more linear levels of BioShock are decorated and designed similarly thanks to the hub nature of spaces in these games and very clever “smoke and mirrors” level design.

Interior in BioShock Infinite
Interior in Dishonored 2
Interior in Thief 2: The Metal Age

Thanks to incredible attention to detail, immersive sims are shining examples of environmental storytelling techniques — spaces can tell a lot about people living there. A throne room in Lord Bafford’s Manor from Thief: The Dark Project implies that the rich man tends to think of himself as of a very powerful person, and he also has a large library with hundreds of books (“I wonder if he reads all of them, or it’s just for show?” — Garrett asks). A large network of hidden passages in Lord Gervaisius’ house from Thief 2 probably means that the owner likes to travel around the house unseen and unheard. The items in James Miller’s apartment in Deus Ex: Mankind Divided, such as personal photos and notes, say a lot about the character’s past.

Immersive sims also prioritise meaningful production values, such as visuals and sound design, which are, coupled with believable level design and attention to detail, result in incredibly rich, deep and immersive atmosphere. It’s not a coincidence that immersive sims are among the scariest and unsettling video games in history — System Shock 2, BioShock and Thief are all great examples. Even though few immersive sims have been AAA-budget games, the necessity of reasonably high production values are important for establishing proper immersion.

Laser focus on each and every detail, as well as environmental storytelling, means that all immersive sims are “an inch wide and a mile deep” — compared to most other games, let alone open world games, their locations are relatively small and can be run through quickly if needed. This is one of the reasons why first person open world games such as The Elder Scrolls series, Fallout or Far Cry philosophically are very different from immersive sims — by focusing on scale, these games inherently compromise on details and low-level systems (“a mile wide and an inch deep”).


By nature of being games set in very believable spaces inhabited by characters which stories can be effectively told through a variety of techniques, as well as empowering players with means of making meaningful choices, it’s natural that immersive sims have always been very well positioned to tell impactful stories and let players interact with certain situations which could make them stop and think about consequences of their actions. It’s not surprising that many immersive sims have some of the most intelligent and thought provoking stories in games.

Immersive sims either convey messages their authors believe in, or present players with difficult narrative choices. In System Shock series, players face horrors of AI going rogue and tricking people into traps, slowly corrupting their minds and ruining lives — if anything, decades later, the narrative about dangers of AI has only become more relevant. Prey is a deeply touching and thought-provoking story about personal relationships within the context of smart sci-fi themes, with players in control of the fate of many people on Talos I. BioShock series portrays dangers of extremes — the first and the second games in the series depict how societies can be ruined by both radical individualism and collectivism, whereas BioShock Infinite is a brilliant anti-utopia set in xenophobic alternative reality version of late XIX century USA. Before BioShock, Thief series also focused on dangers of extremes — The Dark Project is about radical environmentalism, whereas The Metal Age depicts horrors of uncontrolled technological progress. Deus Ex series is perhaps the greatest example of the game series focusing on mature matters — from smart socio-political critique to exploring conspiracy theories and effects technological progress and biological augmentations can have on society, Deus Ex games present players with different choices that radically affect the future of the world depicted in the games.

JC Denton decides the fate of the civilization at the end of Deus Ex


Crystallised in the 90s by Looking Glass games, all these five core pillars of immersive sims continue to define the games of this design school to this day, and despite current marketing problems and overall crisis of single player games, the future for immersive sims looks bright to me. Development of these core pillars are very aligned with the technical progress of video games — as computers and consoles become more powerful, immersive sims would feature bigger and even more detailed levels and better tools, more complex systems and smarter AI, more choices and consequences, and even greater production values and immersion. The two areas with the most promising potential are AI and physics — we have been only scratching the surface of physics-based systems, and one day we will be playing immersive sims were we would be able to break entire walls using explosives, bring down wooden structures by putting them on fire, and creating electrified water traps by making holes in pipes.

Let’s hope that upcoming immersive sims, such as Underworld Ascendant and System Shock 3, both currently in development by OtherSide Entertainment — a studio full of Looking Glass alumni — would further push the boundaries of this school of game design.

*a term used by Warren Spector for describing immersive sim design