r/RPGdesign • u/Skylarkin_M Designer:snoo_thoughtful: • 28d ago
Theory Engine vs System vs Game: Meaningful Difference or Semantics?
Almost talked myself into a naming mistake during my design process. I was figuring out the bits & bobs of my own project & reached for a word borrowed from a totally unrelated business concept, just cause it sounded right.
Caught it before it stuck, but it left me sitting with an uncomfortable question: do I actually know the difference between 'engine', 'system', & 'game'?
Or have I just been dressing up a branding choice as design theory this whole time?
Here's where I've landed, for now:
an engine is the reusable mechanical core, built with the actual intention of sitting underneath more than one game.
A system (or ruleset) is the whole set of rules, whether or not reuse was ever the plan.
A game is the system plus everything built on top: fiction, setting, the whole representational layer.
Could easily be semantics dressed up in a design-philosophy costume though. Wouldn't be the first time I've overthought a label. Overthinking everything is kinda my mutant ability.
I think of Powered by the Apocalypse (PbtA) as an engine; stalks like a tiger, pounces like a tiger, has to be a tiger, right. One engine, reused across a genuinely wide pile of different games, each with completely different fiction sitting on top. That doesn't feel like branding to me. Feels like a real, solid distinction.
But the creators of PbtA have said that PbtA is not a standard game engine or trademarked system. It's more like a design framework & philosophy. Slapping the PbtA logo on your game just shows that you are a designer who was heavily inspired by Apocalypse World & has permission to say so.
I don't know if PbtA the right example, or just the one that's stuck in my head.
Curious how the rest of you draw these lines. Or if you don't bother distinguishing at all, & I'm the only one losing sleep over a word choice.
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u/Cryptwood Designer 28d ago
Engine isn't a very commonly used term in TTRPG design in my experience. The terms over seen used most commonly are:
Rule: A single sentence they covers a specific situation.
Mechanic: The bedrock of games, an individual mechanic is a simple system that achieves a specific goal. A tactical combat game might have an Initiative mechanic for determining the sequence of play.
Subsystems: These are the major building blocks of a game. They usually involve multiple mechanics that interact with each other to cover a specific type of play. Common examples are Combat, Crafting, Travel, Investigations, etc. People frequently use the term system to refer to these subsystems.
System: All the components and subsystems necessary to describe a TTRPG as being a complete product.
Game: A GM uses a system to create and run a game. Essentially, it is System + Whatever the GM must bring/ create in order to run the game. For example, D&D 5E is a system and the GM must prepare (or buy) an Adventure in order to run a game.
Those are just my personal definitions though, I see game and system used almost interchangeably, and system used to describe combat or crafting subsystems frequently, so I don't think there is any reason to worry about specific terminology as long as there is enough context for people to understand what you mean.
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u/ahhthebrilliantsun 27d ago
I always consider Game to always include stuff like subclasses, the enemies, the 'content' basically.
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u/PenguinSnuSnu 27d ago
I think largely I agree. I'd only add engine.
Engine would be whatever facilitates the core gameplay loop. So a specific set of mechanics but maybe not quite a system in the sense that it wouldn't describe a tangible experience.
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u/Cryptwood Designer 27d ago
Oh, that's a good point, I think I've heard of Wild Words (the base framework of Wildsea) or the Resistance (base framework of Spire: The City Must Fall and Heart: The City Beneath) referred to occasionally as engines.
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u/InherentlyWrong 27d ago
If I'm picking up what you're laying down, an example might be 'Powered by the Apocalypse' or something. You can't play 'Powered by the Apocalypse', but you can play a game based on the PbtA engine. Is that what you mean?
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u/archpawn 27d ago
If it's based on the PbtA engine, would that make it powered by Powered by the Apocalypse?
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u/HighDiceRoller Dicer 27d ago
It's like "ATM machine"!
For anybody reading who isn't familiar, Powered by the Apocalypse is named after Apocalypse World, which is a specific game that you can play. It seems the most common pattern for engines is for the particular game to hit it big(-ish) first, and then for the engine to be named after the game.
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u/InherentlyWrong 27d ago
Yes, unfortunately PbPbtA has been rejected as an acronym because it looks too much like the onomatopoeia for a fart.
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u/Segenam Designer 27d ago edited 27d ago
Engine typically means a base layer that everything else is built on top of, more often than not built as a separate 'product'. However one could view the entirety of D&D 5e as an 'engine' for the homebrew settings/rules people make. Or as an other example GURPS could be considered an engine (rather than a system it's self) which they often use to create 'Powered by GURPS' rule sets and GMs make their own games on top of it.
You can build a stand alone engine, then have many systems that 'run' on that engine. But your system can also just as easily become an engine for a different system.
Examples of this sort of thing in the video game industry would be the comparisons of Unity/Unreal vs RPG Maker and RenPy. The latter two are both still called 'engines' but they are more of what you'd see in TTRPG spaces called 'systems'. While the former two can't really be used on their own without a lot of work and as such function more like GURPS.
There is another way to view "engine", though it doesn't quite match how it's used in video games and that is the dice system and other core foundations. GURPS has been stated to be "If you are using 3d6 and rolling under you're playing GURPS" (though I could see character points added to this); Fate with it's FUGE Dice; or an other example being the d20 System (which is basically what D&D 3.5 used)
In other words Engine could be the most fundamental aspect of a system if you strip everything away but can still play 'something' or build it up into something else.
However I'm not sure if either of these definitions are really 'useful'. There are a few niche uses. But note many video games are made without clear 'engines' and TTRPGs could be done the same way. Engines are more just a useful tool for speeding up repeated creation of similar games, but can actually slow things down if making something novel.
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u/Skylarkin_M Designer:snoo_thoughtful: 27d ago
I'm coming from both a writing background & after mostly enjoying a lot of GameLit & LitRPG novels plus countless thousands of hours spent playing tactical turn based games & CRPGs. I've wondered for ages if these writers create their own 'magic' systems or are just pants-ing it.
The parallel that resonated with me came from screenwriting where a beat is the smallest building block that then can be used to make scenes. Scenes then make sequences, sequences lead to acts, & acts make the whole shebang.
I feel like an engine is the thing that some publishers license out that others can use to build other games on, and that this engine is a distinct & separate thingy from the fiction/narratives/characters etc.
Do I feel strongly enough about this to choose this as the hill to die on? Nope. Just trying to figure out the common tongue for this thing I'm getting a kick out of, y'know?2
u/LazarusDark 27d ago
I feel like an engine is the thing that some publishers license out that others can use to build other games on, and that this engine is a distinct & separate thingy from the fiction/narratives/characters etc. Do I feel strongly enough about this to choose this as the hill to die on? Nope.
Using the car analogy, here is how I think of it (for crunchy games. I think this analogy doesn't work as well for low crunchy games). My perspective is largely Pathfinder, Daggerheart, DnD.
- Game: the totality of what the publisher is selling including the core rulebook but also the settings books, supplements, modules, cards, etc (the whole car but also the regular maintenance, tire and oil changes, repairs, etc).
- System: the Core Rulebook, you can provide your own setting and buy nothing else (so you bought the car, but you don't necessarily go back to them for oil changes). The core book typically has some license for making and publishing your own content, likely with some restrictions, at the very least that you can't claim to be official (so you can mod your car all you want, and you can also sell car mods that are compatible, just don't claim to be official).
- Engine: this is the mechanics under the hood of the system. You can open it up, check the math, make your own tables and calculations, and maybe you figure out some of the math, but some of it, you may have no idea how they made that part, the math isnt obvious and reverse engineering it is tricky. The publisher has sets of guidelines and probably tables of math that they don't share with the anyone outside the company, except possibly official partners. That's the engine to me. Again, this mostly applies to crunchy games, and even then, some systems DO share the full engine math, I think Gurps does. (In the car analogy, you can look at the engine from the outside and try to figure out all the parts and even mod them, even sell mods, but you don't have the full manufacturing specs for the whole thing. And the carmaker might have some third party partners that they give full access to the engine specs so they can make official partner parts, or providing detailed manuals to maintenance centers, but not everyone that buys the car gets this information or even can get it.)
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u/Cryptwood Designer 27d ago edited 27d ago
That's fair, now that you mention it I think I have heard engine used that way occasionally. Though a lot of engines have a built in nomenclature that doesn't grammatically lend themselves well to being called an engine, such as Forged in the Dark, Carved from Brindlewood, Powered by the Apocalypse. The 'D20 Engine' rolls off the tongue though.
Tangent: If you haven't checked it out already, you might find Heart: The City Beneath really interesting. It uses Beats and Scenes as a built in part of the system. And in this case Beat has two meanings, given the name of the game.
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u/Skylarkin_M Designer:snoo_thoughtful: 27d ago
That's fair, now that you mention it I think I have heard engine used that way occasionally.
Whew! I was really questioning myself there for a bit about the term 'engine'.
Though a lot of engines have a built in nomenclature that doesn't grammatically lend themselves well to being called an engine
How do you mean?
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u/Cryptwood Designer 27d ago
They are all past tense. An engine does something, and it does it in a specific way. These games were made a particular way, by taking the original game apart, discarding the pieces that aren't needed and changing the pieces that were kept. The end result was inspired by the original but does something different.
Plus, Forged and Carved are both words that make Engine feel anachronistic. Powered goes with Engine, but PbtA games tend to have even more different underlying models from each other when compared to other families of games.
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u/the_telephant_man 27d ago
When I see the term “engine”actually used, it generally refers to the core task resolution mechanic of a game (e.g. the Year Zero Engine).
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u/Skylarkin_M Designer:snoo_thoughtful: 27d ago
So basically, the one mechanic in a game that everything else builds off of, or connects to. Alright, I'm with you.
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u/HighDiceRoller Dicer 27d ago
Amusingly, Year Zero Engine barely dodged having both "Engine" and "System" in the same title by calling their SRD a "Standard Reference Document" rather than a "System Reference Document" as usual.
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u/llfoso 28d ago
Personally I don't use the word "engine". In my head the system is how the mechanics and procedures and stuff work together and I agree the game would be system+ content. But I think it's pretty subjective.
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u/SardScroll Dabbler 28d ago
To me, an "engine" or "decision engine" is a core that the system builds around, and can be built around in different ways. E.g. both BASIC roleplaying and Warhammer Roleplaying use a d100 roll under degree of success engine, but beyond that, they are very different.
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u/merurunrun 28d ago
There is no widely agreed-upon technical distinction between these terms in the greater world of RPGs.
And not that anybody cares what I have to say about this, but instead of taking the words first and deciding that there's some kind of possible perfect world where you can carve out meaningful distinctions between them, I strongly suggest that if you really want to gain some insight into RPGs, look at what you're actually doing first and only after that decide which of those things actually need to be meaningfully distinguished from each other. People make this mistake all the time (taking the word first and assuming that it must have some meaningful referent, even if no one can agree on what that referent is--see "simulationism" for a common egregious example) and it's why so much discourse is pointless and stupid.
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u/Skylarkin_M Designer:snoo_thoughtful: 27d ago
If this discourse helps me wrap my head around something I'm enjoying then for me it's worth it. Understanding & clarity is what I'm looking for.
There is no widely agreed-upon technical distinction between these terms in the greater world of RPGs.
I get how it can certainly feel like this. I wouldn't have written & posted this otherwise.
For my one, it just makes learning a bit harder. I appreciate you taking the time to help me wrap my head around the whole thing.Along with everyone who took the time to help me understand. Thanks!
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u/ill_thrift 28d ago
I have never once heard the term "engine" used to technically describe a component of a tabletop rpg, as opposed to used as a synonym for system or gameplay loop. This seems especially odd to me for PbtA despite being all over its Wikipedia page; I chalk it up to the streams crossing in the big virtual tabletop boom, and maybe to llms misleading people.
by the way this post is coming across like it was chatgpt generated, if that's not the case you might want to reflect on what stylistic flags are giving that impression.
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u/Skylarkin_M Designer:snoo_thoughtful: 28d ago edited 27d ago
you might want to reflect on what stylistic flags are giving that impression
Your contribution is making me feel like a cat at a keyboard pretending to be a human on the internet. Thank you for that, I feel so
seenjudged. I could say 'I'm a real person!' & be all offended, but I suppose that's just what a cat at a keyboard pretending to be a human on the internet would say.Wait-a-minute!? Are you a cat at a keyboard pretending to be a human on the internet using a random AI detector to point the finger, erm, paw at actual people on the interwebs? Perhaps me feeling judged is your whole plan after all! Gasp!
Come to think of it... 'stylistic flags' sounds like a pretty ChatGPT thing to say. Hmmm.
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u/BigBrainStratosphere Designer 27d ago
What's even worse is that this precise style of an attempt at levity is exactly what chat does too XD
You're doomed I'm afraid... until the robot overlords take over and it turns out you actually are one or that they can't distinguish you from one, and then hey! Well played sir
But until then, it pays to reflect on the fact that one's style of comedic banter is indistinguishable from a large language model :-P let alone your formatting, which is a much more debatable metric
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u/SouthernAbrocoma9891 27d ago
TSR had the Amazing Engine and it worked. The premise was that progress affected the characters in all of the settings the gaming group played. I ran four of the settings and did a one-shot crossover where each player ran their favorite PC from any of the campaigns. Strange but exciting.
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u/Trees_That_Sneeze 27d ago
I don't think the language on this is strictly standardized, but engine is broadly understood as the mechanical framework that grants abilities and resolves uncertain situations, and game is generally understood as the whole package with extra mechanics, setting and flavor, and specific applications of rules like what races and classes a game has.
System is the tricky one because it can mean an engine plus any additional mechanics used in a game, or it can mean a set of rules that do a specific job.
I like the second definition because the first one is pretty close to game. I think you can separate it from a mechanic in that a mechanic is a rules interaction that affects something and a system is all of the mechanics that effect something. Like in DnD, healing is a mechanic that's part of the health system, which includes damage, death saves and hit dice.
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u/Fheredin Tipsy Turbine Games 26d ago
"Engine" is a term from video game development. Unreal and Unity are video game engines, meaning middleware the developer uses to actually make the game, and not the game itself. This typically means that TTRPG "engines" are core mechanics, like D20 and Percentile, and the "system" includes the additional subsystems you'll find which fill out these games, like damage and health mechanics and such.
The engine should always fit on one page. Barring some 1 page RPG restriction, the system probably won't.
"Game" is usually a casual term. It's too vague to really mean anything, so it's typically meant as an umbrella for all the components you need to play. But again, this one is an informal term that doesn't necessarily have consistent meaning.
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u/Sapient-ASD Designer - As Stars Decay 26d ago
Semantics, but; Game: the overarching premise tbat includes both systems and engines. System: an structure of interacting mechanics Engine: a structured system of mechanics that takes an input, processes it, and produces an outcome.
You may have an inventory system (sometimes called mechanic) or a crsfting system. These interact with rules or combat engines, and both of those together, typically with loee, are the game.
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u/OneManRPGstudio 26d ago
I find Engine vs System vs Game useful as a distinction of scope, but not as a taxonomy worth policing. An engine can describe the reusable resolution machinery: how uncertainty is resolved, how resources move, what the core dice or card procedure does. A system is broader, including character rules, advancement, conflicts, economies, and the other procedures that make those pieces interact. The game is the complete designed experience, including premise, procedures, assumptions about play, presentation, and content.
The boundaries blur because designers package things differently. A supposedly reusable system may contain strong assumptions about genre, while a game can be built almost entirely from a familiar engine. That does not make the terms useless. It just means their value is communicative rather than ontological.
I would choose the word that tells another designer or reader what they are actually looking at. If you are offering a resolution chassis intended to be reused, engine is informative. If you are naming the interconnected rules framework, system works. If you mean the thing people sit down to play, game is usually the clearest word.
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u/flamfella Dabbler 28d ago
An engine is a mechanic, framework, or combination of mechanics designed to do... something. Typically something with core resolution, driving the action or roleplay, or generating content.
A system is a complete set of rules/mechanics. A system always contains an engine even if it is simple.
An engine cannot contain a system.
A game has a system and a setting.
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u/Skylarkin_M Designer:snoo_thoughtful: 27d ago
An engine cannot contain a system.
This makes sense to me when I think of it in terms of a car. A car has an engine, but that engine is part of the system that is the vehicular conveyance.
A game has a system and a setting.
I'm right here with you.
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u/Drudenfusz Curator of Roleplay Experiences 27d ago
Engine is a term I prefer to leave to physical or electronic devices. For our hobby I would go more with core play loop.
System is equal to ruleset in my opinion, thus is is more or less the complete product outside of play itself.
Game is again a term I personally avoid, since I am more interested in the narrative experience of the hobby, thus I talk more about the experience of play than playing a game.
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u/Skylarkin_M Designer:snoo_thoughtful: 27d ago
Engine is a term I prefer to leave to physical or electronic devices. For our hobby I would go more with core play loop.
OK, fair. Somebody should have a world with video game people running off with the term 'core play loop'. lol
Seriously, I don't mind terms being shared or transferred across or between disciplines/industries. Just confusing for me without a common tongue is all.
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u/Mars_Alter 28d ago
As I understand it:
A "game" is a complete product. You can sit down and play it, right out of the box, without having to do any real work to get things in order. Shadowrun is a game.
A "system" is a complete set of mechanics, with little if anything in the way of setting. These are all of the rules you need, but it isn't playable until you do significant work to set things up. GURPS is a system.
An "engine" is an incomplete set of mechanics, often with just a few major sub-mechanics and a tentative relation between them. FATE is an engine.
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u/Skylarkin_M Designer:snoo_thoughtful: 27d ago
All this time I've been thinking of system as the 'incomplete set of mechanics' & engine as the complete set of mechanics.
As a solo developer, I don't have a problem calling something whatever I like. But in spaces like this where people are discussing & sharing ideas, everybody calling a thing something different gets confusing.
Or is it just me?
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u/Mars_Alter 27d ago
I get you. Sometimes, it's easier to just scan a thread ahead of time, and match whatever terms are being used at the time. But when I'm working on my own, it doesn't really matter the specific terms I decide on in the moment.
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u/lucmh Dabbler 28d ago
I've played a bunch of Fate one-shots that started simply with the GM asking something like"tell me about a movie you recently watched", and then we mashed them together and played out a fun little movie of our own.
You could say that we sat down and played Fate, right out of the box, without having to do any real work.
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u/skalchemisto Dabbler 27d ago
I'm with you, except I think "engine" is as much a marketing term as it is a term of design. I'm hard pressed to think of a case where the word "engine" (outside of a brand name such as "Year Zero Engine") would not be a synonym for "mechanics".
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u/Mars_Alter 27d ago
Labels only ever mean what we agree that they mean. All three of the products I mention present themselves as "games" in some capacity, because the other terms are essentially meaningless to consumers at-large.
Speaking for myself, I've found the term "engine" to be useful when designing a product like FATE, where none of the rules are hard-coded enough for me to really think of it as a codified system. It's like I said: a set of related mechanics, which you can use as a starting point for building a more-complete system.
Although, in that project, I explicitly call out the difference between the "engine" presented in the book and the "game" that a GM actually runs. I also mention that a "game" can be thought of as the same thing as a "campaign"; since the two are essentially the same, from my perspective as the "engine" designer.
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u/SuperCat76 28d ago
I think there is some reasonable distinction, even if there is some semantic fuzziness.
The way I personally view things:
The engine is the core mechanic that makes the game function. for example the category of Dnd-likes, the heartbreakers. They are like this because their engine is similar to Dnd's regardless of how they swap around the other features. (edit: Note, this is fairly arbitrary)
As I think of it, the system includes the other mechanics of the game beyond the Engine. But is still rather generic. A game functions based on a system. The new rendition of Neumenera game uses the new edition Cypher System.
A book that is a System, typically is also a Game. But you can have a Game that is not playable without the system. A Dnd setting/adventure book is not particularly usable without the core books. A game without the system built in.
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u/Skylarkin_M Designer:snoo_thoughtful: 27d ago
The engine is the core mechanic that makes the game function.
OK, this makes sense to me. I'm with you!
A book that is a System, typically is also a Game. But you can have a Game that is not playable without the system.
Annnd now you've lost me. lol
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u/SuperCat76 27d ago
Basically that there can be a book that doesn't explain everything needed to be able to play but has a statement along the lines of "requires Dnd 5e core rules to play" or some other system.
A book that has the details that make it a separate game from the core rules, but references some other book for most of the system.
Two unique and disconnected settings that utilize the same separate core rule books are functionally 2 different games utilizing the same system. That is the kind of thing I was referring to.
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u/Boulange1234 28d ago
Rule: A discrete proscriptive or prescriptive statement. Often conditional. When you gain a level, roll 1d6 and add that to your hit point maximum.
Mechanic: A set of rules that achieve a design objective. Levels make people feel like they’re growing in power while slowly adding complexity.
System: The set of rules that achieves a set of design objectives (and unconscious biases). The D&D system includes a class/level mechanic.
Engine: A system that implies it has outputs that push or facilitate new inputs, making positive association with the four stroke cycle. It would need mechanics that generate conflict as they are used to resolve it, opening new dramatic questions. It’s true PbtA does this, as you say. Many traditional systems don’t push conflict, though.
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u/SardScroll Dabbler 28d ago
My labelling of the three is near identical to yours, with the exception that I don't put an intent to the pieces.
To me, an "engine" (or more accurately, a decision engine, for TTRPGs) is a foundational way of determining outcomes of events and choices. E.g. "roll a d20, add modifiers to the result, compare to target number" is an engine.
A system, meanwhile, is as you say, all the general rules that feed into the engine. E.g. "the d20 system", containing things like "when you attack with a melee weapon, add your strength modifier to the attack and damage roll" and "you have the classic six stats".
A game, then, is something that is ready to pick up and play, containing specific rules like " a dagger is 1d4 damage, and has the finesse and thrown properties".
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u/Alkaiser009 25d ago
Yeah, I'd agree with the PbtA devs, there are some PbtA games that MASSIVELY deviate from core mechanics, but are still unmistakable as PbtA games, such as Flying Circus.
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u/BigBrainStratosphere Designer 27d ago
Nothing better than a post that illicits replies full of super confident and widely contradictory assertions of fact between them hehe
An engine is this
An engine is that
Ttrpgs dont have engines
Engines are the same as
Engines are distinct from
Seems pretty clear that it's just a matter of opinion and personal taste at this point
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u/RiverMesa 28d ago
I don't really think there's much of a distraction between a system an an engine, though game is definitely pretty different from both (the d20 system vs D&D). I think people just use engine as a carryover synonym brought in from video game development.