Why the Hell Does Depth Matter?

Depth is my primary metric of quality for a game. I believe depth is a good metric because it is “simple” and “generic”. Unfortunately it’s not simple in the way of being simple and relatable to understand. It’s simple like GDP is simple. It’s one final number that represents a whole ton of things going on under the hood. Depth is the emergent result of a lot of different things coming together in a game. Depth, like GDP, is a generic metric in that it doesn’t care what’s being invested in, it could be medical, military, education; puzzle game, RTS, RPG, FPS, or fighting game, it only matters what the final outcome is. Depth doesn’t encompass everything about a game, the same way GDP doesn’t encompass everything about an economy, but both are fairly important metrics regardless. Unlike GDP, there are less ways to fake depth and end up with a cheap result.

I define Depth as the number of states that are differentiated from one another, balanced against each other, and currently known about/preferred by the playerbase. State is the current condition something is in at a specific time. A state with regards to games is the current condition of everything present in a game at a moment in time. Depth is the sum of these states after passing through 2 filters: redundancy, and relevancy.

We start with Possibility Space, which is every single state possible. We filter those into Absolute Depth first by removing all states that are redundant, that are just copies of one another, such as rotations or mirror images of the game board in Tic Tac Toe or Go, or more powerful but functionally identical weapons in RPGs. Then we filter Absolute Depth into Relevant Depth by removing all states that are underpowered and therefore not commonly used in play, or the ones that are unknown to the player community at a given time, such as those that use undeveloped techniques or unknown mechanics. The final result is a measure of the effective complexity of the game.

depth venn

Okay, so, why the hell would the effective complexity of a game matter? What does it matter if a game is more complicated? For this, lets go back to Raph Koster’s Theory of Fun. The gist of his theory of fun is that fun is derived from winning at something inconsistently, like a coin flip. Fun is also derived from improving your consistency over time. Something you can win at effortlessly is boring, and something you never win at is frustrating (this is backed up by Flow theory too). Random things can trick the brain, which is why gambling can be fun, but most people eventually catch on and stop playing, unless they delve into superstitions about luck.

However there’s also a bit of a contradiction there, if you improve your consistency over time, then won’t something that’s fun now eventually become boring when you’re 100% consistent? That’s true. Depth gives players many different measures of consistency, so while you may be consistent at one thing, now you have something else to get consistent at.

Raph Koster’s Theory of Fun posits that fun is the joy of learning (probably because learning things makes us better at surviving, so we adapted to reward learning neurologically). A deep game has a lot to learn about. Therefore a deep game is a fun game.

On top of that, the experience of playing a deep game is different from playing a shallower one. Deep games typically have more choices, and more possible consequences for those choices, requiring more complex thought about each choice. Many board games with less board states are easily solved (connect 4, checkers), where more complex ones require more arcane heuristics in order to perform well at (Go). Simpler games are more about doing 1 thing right, where deeper games are about thinking about future consequences more. Deeper games involve more interesting decisions, as per the Sid Meier definition.

Smash Bros Melee might have less buttons and less attacks than a traditional fighting game, but you can get more results from each move than you can in a fighting game, because Smash Bros is highly responsive to the relative positions of each character, and the timing with which attacks are hit. This isn’t to say that Smash Bros is necessarily better than a Fighting Game though, because both a few nuanced moves, and many differentiated moves are equally prioritized under depth theory, as long as they shake out to the same number of relevant states.

Later Smash Bros games did a lot of work to remove a lot of the nuance in Smash Bros Melee moves, by making them less responsive to differences in timing and spacing (less sweet/sour spots, reverse hits no longer work), by reducing the effect of defensive mechanics during combos, and removing options outright. These games are comparable in their options, but have less depth. This makes progress less clear, since there are no longer an array of clear techniques and strategies to master, and requires players to work harder to get smaller rewards for their effort.

13 thoughts on “Why the Hell Does Depth Matter?

  1. Mason Spangler May 23, 2020 / 10:42 am

    The specific patterns of options available to a player at any given time, and how they move from one state-space to another, is also a factor in game quality that shouldn’t be missed.

    Consider a fighting game that used the entire keyboard, each button performing a different attack. Compare this to the way Soul Calibur matches small groups of moves to states. Both could be identical if you set them up as such, but the latter feels infinitely more intuitive and /more fun/ to play.

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    • Chris Wagar May 23, 2020 / 10:47 am

      That’s UX. It’s in the list of priorities, it’s just not as important as depth.

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  2. Mason Spangler May 23, 2020 / 2:25 pm

    UX as in user experience? I mean broadly the entire game is the user experience, and much more specifically doesn’t UX just refer to small quality-of-life features?

    I’m talking about fundamental game feel, like the pattern that non-redundant states are presented in. In a game with 10 non-redundant states (like a Game & Watch game), depending on the game the amount of moves you will have from any given state, and the flowchart of which-states-leads-to-which-other-states will be completely different without affecting depth in the way you’ve described here.

    Assuming we’re on the same page, responding to “it’s not as important as depth”… I feel like that’s only true if you’re comparing games that lack depth (say, tic-tac-toe) with those that have it in spades (say, chess).

    if you were to compare Chess with Go, Go is unarguably, hugely “deeper” in the way that you’re describing, but once the game is complex enough that people can reasonably spend their whole lives on the thing, “UX” is really all that’s left to distinguish one demographic from another.

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    • Mason Spangler May 23, 2020 / 2:34 pm

      ignore the first paragraph – lol, I googled UX. the rest still makes sense though pretty sure.
      also apologies for not ‘replying’ to your comment properly, hopefully this works better

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    • Chris Wagar May 23, 2020 / 2:55 pm

      “UX as in user experience? I mean broadly the entire game is the user experience, and much more specifically doesn’t UX just refer to small quality-of-life features?”
      UX is a pretty wide field. I think keybinds count under UX.

      The number of buttons, or the particular binding of buttons is not (usually) included under game feel, according to the book Game Feel by Steve Swink. Control metaphors are a part of game feel (they affect the real-time control aspect), but largely game feel is about what happens on-screen.

      “the flowchart of which-states-leads-to-which-other-states will be completely different without affecting depth in the way you’ve described here.”
      That’s pretty fair. I’ve come up against this before. Something closer to mathematic complexity class arguably makes more sense, but that has its own problems (you can make a simple game in a high complexity class by meeting certain requirements, but only implementing a few elements). I don’t have a good answer to this, state size usually works well enough to not justify a more complex definition. If you want to be technical, it’s about the edges instead of the nodes (there must be at least as many edges as nodes, minus one, for all states to be connected, so number edges scales as fast or faster than the number of nodes). I’ll consider including this technicality in the future.

      “once the game is complex enough that people can reasonably spend their whole lives on the thing, “UX” is really all that’s left to distinguish one demographic from another.”
      I don’t agree, games of similar depth can have different possibility spaces. The difference between Starcraft and Quake 3 isn’t just UX. And Go is a way better game than Chess, there isn’t like a cutting off point. But you did bring up something I overlooked in writing this article, but meant to include. Deeper games have more choices, which changes the moment-to-moment experience of playing the game.

      I have a list of priorities, it’s linked in the top bar, under “About & Best Posts”, here it is:

      1. Depth
      2. Challenge (for single player games, multi has challenge automatically)
      3. Clear Feedback
      4. Game Feel/Kinaesthetics
      5. User Experience
      6. [none]
      7. Quality of Graphics/Sound/Animation/Story

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      • Mason Spangler May 23, 2020 / 4:25 pm

        Thanks for such a well-thought out response! My terminology is a bit clumsy so you’ve given me a lot to work with here if I ever bring this up with people in the future.

        Number/binding of buttons is kinda just heavily abstracted control metaphors? If I’m correctly understanding what control metaphors are. So regardless, game feel covers that nicely, excluding the loose connection it has to the more nitty-gritty depth/complexity stuff.

        “I don’t have a good answer to this” – speaking as an aspiring game dev, me neither. Feels more like art than science. I think it’s interesting though because it is the only distinguishing factor between two games of perfectly equivalent depth (it defines the shape of a possibility space, right?), and I also consider depth my #1 priority.

        I consider Chess and Go both past a real world cut-off point that most people could reasonably play them their entire lives without ever coming close to their respective ceilings. Surely this is no different than arbitrarily distinguishing between “effectively redundant states” and “objectively redundant states”. I feel both games are effectively “good enough” such that even small blemishes don’t destroy the foundation, they merely add texture for the people who enjoy them.

        I mean, removing Wobbling from SSBM might make it deeper? It’s a pretty easy argument to make considering all of the ICs chain-grabs it makes redundant.

        Personally though, I enjoy wobbling because there’s nothing else in competitive play that locks you out of inputs for so long. It’s unique in how much pressure it puts on you to avoid getting grabbed, and it’s interesting that it can either give the player time to regain composure, or put them on tilt even worse. Maybe the standards are different when it comes to making a new game, rather than changing an existing one, but I’d be wary of sanding off a game’s unique edge when patching/updating/sequelling if it’s already attracted people with inevitable idiosyncrasies.

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        • Chris Wagar May 23, 2020 / 5:32 pm

          Read the book Game Feel. Nobody reads it and they just assume they know what game feel is. I should probably write an article, “You don’t know what game feel is, read the damn book”, because Steve Swink basically handed cave men the secrets to quantum computing, and everyone decided to ignore it and assume what game feel is based on the title.

          The short is, game feel is the wrong term. Beyond that, even in a hypothetical FG where every attack is on a separate key, it’s still a hell of a lot more important to have a bunch of differentiated attacks than to have 60 versions of the same attack. It’s more important to have depth than simple keybinds.

          “I mean, removing Wobbling from SSBM might make it deeper? It’s a pretty easy argument to make considering all of the ICs chain-grabs it makes redundant.”
          It would make ice climbers deeper. It would make the game shallower, because then you’d no longer have ice climbers as a viable character, which we saw when all the icies mains retired after the wobbling ban was put in place. Also, redundancy doesn’t refer to balance, that’s relevancy.

          “I consider Chess and Go both past a real world cut-off point that most people could reasonably play them their entire lives without ever coming close to their respective ceilings.”
          Chess masters are tired of memorizing endgame solutions and have been for decades. Go Masters are still learning new heuristics. Sure, the ceiling is up there, it is for a lot of games, but Chess is at the point of squeezing water from a stone. Less depth means you end up working a lot harder for marginal advantages.

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          • Mason Spangler May 24, 2020 / 5:35 am

            I don’t use the term ‘game feel’ personally, you kinda suggested it and I’m just trying to use terminology you’re most comfortable with. Intended to read the book since you mentioned it last comment, but I’m not that quick.

            Also I’m not saying anything about “60 versions of the same attack”. You would have all the exact same options you would otherwise, only in Soul Calibur it might be “double tap forward, press A, hold K, tap B, where-as in the game I’m suggesting all of those inputs would be macro’d to a single button. Is this not ‘heavily abstracted control metaphors’? You press a button to simulate the act of a character performing an action.

            Redundancy as a literal word and not some obscure piece of game design terminology makes as much sense as relevancy in the context I used it.

            “Chess masters are tired of memorizing endgame solutions and have been for decades.”
            Well, yes. But they still can’t beat AlphaZero. The ceiling approaches, but is not ‘within reach’.

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            • Chris Wagar May 24, 2020 / 6:27 am

              You used game feel first in this comment thread. You can double check terms in my glossary if you want. It’s probably not the best idea to pick the first term that comes to mind in order to appeal to me. Use plain english if you can. You don’t need to use fancy design terminology. If you don’t really get all the terms, then you don’t have to use them haphazardly to like, stroke my ego or whatever.

              To address your example directly, Soul Calibur with 3 buttons vs Soul Calibur with a keyboard’s worth of buttons isn’t significantly different as a game. It suffers a bit in UX, but it would have bigger issues if the moves weren’t distinct than it having an annoying control scheme. It’s more important for the moves to be different in function than for it to have a convenient control scheme, basically. UX is a lower priority than depth. That’s my core point. It’s about priorities.

              “Redundancy as a literal word and not some obscure piece of game design terminology makes as much sense as relevancy in the context I used it.”
              They’re my terms. I used to use redundancy the way you did before integrating the filter for relevancy. There’s an image dead center in this article explaining the difference.

              “Well, yes. But they still can’t beat AlphaZero. The ceiling approaches, but is not ‘within reach’.”
              Human players don’t play the same game as AI. They’re hitting an asymptote. They might always be able to go higher than before, but for less and less reward.

              Maybe my terms are silly or whatever, but if you’re on my blog, the primary source of my terms, it’s not exactly fair to call them obscure.

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              • Mason Spangler May 24, 2020 / 7:07 am

                I consider terms like ‘game feel’ and ‘UX’ to be super wishy-washy. But that’s because my idea of game design comes from a time when those things were just called “game design”. I’m not trying to use clever sounding words, I *am* trying to speak in plain english, but the uber generic terminology gets in the way of that. You’re right though I did bring it up first, so my bad.

                I think you’re under-selling the importance of control scheme. It isn’t just about convenience, it reflects the way the game feels to play (which I guess isn’t technically “Game Feel” – nice.) on a very fundamental level.

                And redundancy isn’t ‘your term’, not as I was using it. It’s a word. I was using it per its literal dictionary definition. It would be REDUNDANT for a player to learn how to hand-off when they can wobble, because in a competitive environment wobbling achieves all the same things and then some. It is REDUNDANT to include it as an option, for this reason. This is literally what redundant means, and it is only a coincidence that you used it differently earlier. Kind-of a meaningless point to argue further tho.

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                • Chris Wagar May 24, 2020 / 7:26 am

                  Well, take my word for it, they’re specific and consistent, not wishy-washy. The eponymous book Game Feel was very specific and unambiguous in what is or isn’t game feel.

                  I think I’m allotting the proper importance to a good control scheme. https://critpoints.net/2018/03/07/weird-controls-are-good-for-you/ You’re going to need a more concrete argument than “it affects how the game feels to play”. Depth is more important than having all the buttons grouped together, but both things are still important.

                  My bad on redundancy. I see your point. I didn’t realize you were using it that way. My original point stands. Yes, removing wobbling would make ICs deeper. No, removing wobbling would not make the game deeper without appropriately compensating ICs for their loss, see Project M, where they did this (though ICs are still not popular). Without wobbling, ICs as a character fall out of relevance.

                  If you plan to reply, please do so in a new comment, WordPress is dumb.

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  3. Mason Spangler May 24, 2020 / 7:33 am

    I do take your word for it. 🙂 Probably came across more snarky in that paragraph than I meant to, really what I was saying was “I’m an outdated fossil on these matters – don’t mind me” haha

    And yes perhaps your priorities are in check, might need to read some more of your articles to determine how much they even align with mine, considering how poorly I’m understanding what would fall under depth, game feel and UX respectively.

    I don’t think enough time has passed yet to definitively say that ICs have fallen out of relevance, nor to blame a wobbling ban for it happening in the short term (Wobbles and Fly don’t play anymore, and Chu is getting too-old-for-this-shit. All the modern ICs had wobble-focused playstyles and couldn’t pivot or landing desync their way out of a paperbag), but that’s another tangential argument to have.

    If there’s one thing we can definitely agree on, it’s that WordPress is dumb. If I construct a sounder argument in favour of valuing control schemes/the feeling of gameplay alongside depth, I might message it to you through twitter or something?

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    • Chris Wagar May 24, 2020 / 7:52 am

      I try to make my articles the opposite of vague or wishy-washy to the highest extent.

      “If I construct a sounder argument in favour of valuing control schemes/the feeling of gameplay alongside depth, I might message it to you through twitter or something?”
      Go ahead, my DMs are open. I do value control schemes and game feel along with depth though. My BOTW review has me hack my Wii U to get a better control scheme after all. I talk about control schemes and binds a lot, but they’re a road to get to where you’re going, rather than a means unto themselves, usually.

      Fly didn’t have a wobble focused playstyle, but wobbling certainly made the character more powerful. In an ideal world we’d move to SD remix or Project+.

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