To echo what
the guynecologist and
DJOGamer PT have said:
https://rosodudemods.wordpress.com/2020/12/14/immersive-sim-is-a-design-philosophy-not-a-genre/
“Immersive Sim” is a Design Philosophy, not a Genre
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In brief, I’d argue that a game consists of mechanics (actions the player can take), systems (rules governing interactions), and some form of challenge brought on by a goal. Typically, game genres are thus classified according to their mechanics, systems, and/or structure of challenges. First person shooters are defined by shooting mechanics; role-playing games by character development systems; roguelike/lite games by procedurally generated challenges with permadeath, etc. It is worth noting, then, that the canonical Immersive Sims share relatively few of these basic elements between them. Ultima Underworld (along with Arx Fatalis) is a dungeon crawler RPG set in a single interconnected game world. System Shock is a dungeon crawler FPS hybrid with the same world structure as Ultima Underworld but none of the NPC interaction and no RPG elements. Thief TDP and TMA are mission-based stealth action games with no RPG elements, minimal shooting, and linear progression of levels. System Shock 2 is an FPS/RPG similar to its predecessor but more focused on combat and character building than nonlinear exploration. Deus Ex is a stealth action/FPS/RPG where each mission can span multiple levels which cannot be returned to once the mission is complete. There are barely any shared genre trappings between every one of these games other than being real-time and playing from the first-person perspective – rather, they tend to hybridize elements from various game genres. However, most would agree that there is a design through line that intersects them all, owing to the collective sensibilities of their creators. Thus, the Immersive Sim describes a
design philosophy rather than a genuine game genre in its own right. Given the small number of concrete commonalities between classic ImSims, any classification should ideally be constructed from the minimal set of characteristics shared between them all. The qualities that I believe characterize the Immersive Sim design philosophy are as follows:
- Real-time gameplay from the (usually first-person) perspective of a single player character
- Influence from role-playing games, particularly in promoting player agency
- Systems-driven gameplay with a focus on simulation
As I understand it, “Immersive” comes mostly from #1 since the player is directly behind the eyes of the player character in real time (this is debatable as immersion is a higher-order result of various factors which are highly subjective), and “Sim” mostly comes from #3, as the rules (systems) that define gameplay are largely derived from simulating interactions with the game world in a believable manner. The biggest thing that the name misses is #2, which is a subtler element to pin down since it’s both a comment of history (i.e. the ethos of Ultima Underworld was to make an immersive dungeon crawler RPG that replaced dicerolls with computer simulation wherever possible) and also of structure (the player should have open-ended goals that allow them to apply the various tools at their disposal in a logical manner). It’s #2 that seems to draw most players to ImSims as a sort of secret sauce that holds the experience together. Moreover, it’s more of a design goal than a descriptive quality, and thus has a subjective component that makes it rather difficult to concretely pin down. However, we can look for examples in classic ImSims.
[...]
the guynecologist has explained how Dark Engine games implement simulated systems on a technical level, and my article gives some concrete examples of emergent gameplay on the player's side (see also my
article on player agency for examples of emergent
challenge which is often overlooked compared to emergent
strategies). The essence of the design philosophy is that Immersive Sims should be systems-driven (rather than mechanics-driven, as in a beat 'em up/platformer/shooter), those systems should be simulationist (rather than abstract, such that you can use real-world logic to intuit the rules). These together make for emergent situations as the entities in the simulation interact according to consistent rules. Players coming up with solutions the designer didn't anticipate is a good shorthand, but emergence is really about gameplay emerging from a multitude of elements interacting that are so numerous as to be chaotically unpredictable, and thus engender agency and depth.
Ultima Underworld, being the oldest examplar of this tradition, absolutely qualifies because of how much simulation they crammed into every element of the game. Every item has physics; there's a passage of time that makes you hungry, makes torches go out (even while sleeping), and makes food get stale/rotten; clothing and weapons degrade with use; weapons impart realistic damage to doors at a cost; and of course there's the grammatical rune-based magic system that lets you manipulate objects in a ton of interesting ways beyond casting magic missile or buffing strength, such as grabbing repairing objects, grabbing items telekinetically, barricading doors, enabling night vision, silencing your footsteps, or concealing your body. The NPC interactions are surprisingly deep beyond the clever dialogue which proceeds in a typical modal interface (though it's worth harping on just how clever the writing is, from having to learn the lizardman language to mountainmen becoming irate if you call them "dwarves"); every creature has a disposition towards you which can change depending on your actions beyond just attacking them, such as forcefully demanding their items during a barter (which entails trading actual objects moreso than money); different creatures detect you based on sight and sound perception, such that you can escape and hide from alerted enemies by extinguishing your torch and wearing softer boots. The skill system, despite some major flaws in balance, is designed to enhance the simulation by representing your player's senses, knowledge, and training, such that the Lore skill is as useful as any of the combat skills as it allows you to surmise the utility and state of objects that most games would convey to you automatically by simple omniscience.
Does the Elder Scrolls have some of this too? Well yeah, of course, because Arena and Daggerfall were directly inspired by Ultima Underworld. Bethesda opted for breadth over depth with procedurally generated content in their massive worlds, but you can see a lot of the same ideas and intentions at work, some persisting even as far as Oblivion (with most of these elements discarded by the time you get to Skyrim). I think it's worth noting that the survival needs, passage of time, and object simulation in Ultima Underworld play a much bigger role than similar systems play in The Elder Scrolls, which to me indicates that they weren't working with the Immersive Sim design philosophy writ large, though you'll of course find similarities as they tried to create immersive worlds with tons of player freedom. Going in totally the other direction, you'll even find similarities even with Half-Life, which for all its scripted setpieces still has a core of simulation at the heart of its AI design, player toolset, and obstacles constructed from reusable game elements like tripwires, headcrabs, crates, explosives etc. Deus Ex lead designer Harvey Smith has a
good write-up on Half-Life from back when he played the game in 1998 which touches on these aspects. It's clearly not an Immersive Sim as you're railroaded down a single path which is designed to always reset you to a certain baseline in resources and character state with not a whole lot of variation in approach, but you can see that Valve were inspired by the likes of System Shock just as much as Doom.
I'd argue that the technical implementation of ImSims doesn't
necessarily matter, because while the Dark Engine was extremely ahead of its time and truly built for purpose in creating simulated game worlds (see Tom Leonard's
Thief postmortem for more on its strengths), Ion Storm managed to staple Deus Ex onto Unreal Engine 1, which uses a traditional object-oriented singleton design pattern where everything is an object and all the interactions are coded explicitly in the methods of each class which hold references to manager objects to deal with global state. Having spent 2 years modding Deus Ex and 3 years modding System Shock 2 I can tell you that DX's codebase is truly heinous stuff, but it still checks all the boxes because the totality of explicit interactions between game entities still manages to create deep and engaging player-driven gameplay. As
Warren Spector noted, a lot of Deus Ex's simulation is really just faked with smoke and mirrors due to the limitations of Unreal, and ultimately
Harvey Smith led the team to shift the game's design towards granular RPG upgrades and resource management because the original attempts to build organic simulated interactions between player mechanics and game entities wasn't sufficiently interesting. What they landed on was an adventure/stealth/FPS/RPG hybrid that is lauded mostly for its excellent level design. Even though the skill/aug balance was piss poor, the ballistics simulation laughably lopsided, and the stealth AI dumb as rocks, we remember exploring Hell's Kitchen for intel on the NSF's illicit EMP generator, seeing the path from Osgood and Sons branch out from the laser tripwire basement to the sniper-guarded rooftops or from the explosive-laden alleyways to the sewers which each lead to a different level of the warehouse, whose generator can be destroyed by hacking a computer or using a password obtained from a hostage earlier in the level, or just blowing it up with explosives. That's when the game clicked for me, at least, and though now I can see all of the little tricks they used, there are few games that can pull off that sense of a real world with real rules that I had to understand and plan around to achieve my goals. The other games that come to mind are other ImSims like Thief, System Shock, Underworld/Arx Fatalis, and Pathologic 2.
As an aside, C++ style object-oriented programming can go fuck itself. How such an inefficient and overwrought mess became the dominant programming paradigm for every application, I'll never know.
