A few weeks ago I read this tweet:

In summary:

design your game’s level pacing the way this image designs its sentences pic.twitter.com/3Ws3XysyIa

— MOOMANiBE (@MOOMANiBE) June 22, 2017

The linked image is reproduced below, in case the twitter embed breaks at some point:Obviously, pacing in games is very important, but this comparison got me wondering about how exactly you pace games which focus on puzzle-solving. It’s not that I haven’t thought about this at a subconscious and abstract level. In designing Taiji, I care very deeply about making sure that the game is as interesting as possible, and this often means addressing pacing, at least in some hand-wavy way. But, I’ve mostly been playing by ear, and I haven’t put forth my approach as a formal set of design guidelines.

I did give a semi-formal lecture on puzzle game design a couple of years back, intending it to be a bit of an elaboration on a lecture given by Marc Ten Bosch and Jonathan Blow in 2011, taking those ideas and expressing them as a practical set of rules. I thought it might become a useful resource for beginning puzzle game designers, which seems to have been validated by some of the responses I’ve received. Watching it is useful in understanding the design approach that I use, but because it is so high level, there is still a large amount of intuition required when the proverbial puzzle design rubber meets the road. And furthermore, it doesn’t really say what pacing in a puzzle game is, much less how you should go about improving it.

So, where do I go from there?

I actually spent around six months working on a video essay about The Witness, wherein the explicit goal was to use that game as a case study for exploring the details of good puzzle game design. In particular, I find The Witness to be a standout example of non-verbal communication of ideas through gameplay (Conveyance), both when it comes to teaching the player new mechanics through play, and more remarkably, the way in which the mechanics combine to express something fundamental about humanity’s search for Truth. However, in my writing and editing process, I got lost in the details of individual puzzles and didn’t manage to connect them to the larger picture of the game.

Although I don’t consider that effort completely abandoned, I still feel I lack the proper words to really express my thoughts about the subtle things happening in that game’s design.

I sometimes get questions or suggestions from viewers on my twitch streams. Sometimes these are good ideas, but when they are bad ones, I tend to take an inordinately large amount of time attempting to explain why I think the idea is bad. I mostly do this because I do not wish to appear as though I am simply a diva who is following his own whims, and is insulted by anyone’s criticism of his creative vision. Rather, I want people to understand that I am working within a design framework, and there are certain decisions which very clearly step outside the framework.

The issue is that it’s only very clear when viewed from inside my own mind, but outside of my mind, the framework is ill-defined because I oftentimes lack the words to really express what I am even talking about fully.

I tend to detest jargon, but sometimes creating new terminology is useful, or even necessary to logically explain the choices that one is making, or to make those choices more effectively.

A good example of useful jargon is the entire field of music theory. Without the abstract concept of playing “in the key of A minor”, we would instead have to rely on everyone’s instruments being tuned into the same key by one person who understands the harmony on an intuitive level, or we would require an inordinate amount of communication and correction among the musicians who wish to play together as a group.

So, the main question that I have been turning over in my mind, is how exactly do I define what I think of as the “ideal” pacing or flow for a sequence. What follows is a first attempt to address that question.

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One of the great things about the structure of Taiji is that the entire game is open from the beginning. The player can choose from several major areas and tackle them in any order that they wish. Sometimes progress in an optional area will be halted because of lack of knowledge of a puzzle mechanic from another area, but there are no artificial barriers to progress. This allows the player to set their own pace, to a certain extent. If they get bored with the nature of a puzzle that they are stuck on, they are free to travel to one of the other areas and think about a different type of problem.

This design could easily be used as an excuse to not care about the internal structure of each area, but I still try to do my best to pace and structure the areas properly from within.

Still, until I read that tweet, I didn’t even think to use the word “pacing” to describe the concern. Other genres have been thinking about pacing for decades, but the primary historical difference between puzzle-solving games and those other genres, is that other genres have core gameplay, and puzzle games do not.

In a shooter, for example, the core gameplay is running around, jumping, and shooting enemies make progress. As the game goes on, you might get new and more powerful guns, the enemies might become more varied or have different movement patterns, but the core of the game is always that same core gameplay. In fact, the core gameplay is why we even call these games “shooters”.

So, one might ask, why would puzzle games not have core gameplay?

The answer, is that some do and some do not.

Disregarding the variety of action puzzle games (such as Tetris) which clearly do have core gameplay, and focusing on the category of puzzle-solving games, there are a two main categories: games with systemic puzzles, and those which feature one-off, ad-hoc puzzles. The main difference being that the systemic ones have core gameplay, and the non-systemic ones do not.

Without core gameplay, it is next to impossible to pace a game. This is why adventure games have such a reputation for ridiculous difficulty spikes and poor pacing. Some puzzles can be solved in a few minutes, whereas others will hold up players for hours or even days. Although the primary gameplay in an adventure game is “solving puzzles”, because each puzzle is entirely different, nothing the player learns in one puzzle can be carried forward to help them solve the next. (There are some exceptions, but this is more due to rigor on the part of the designer than any true systemic underpinnings.)

The great thing about systemic puzzle games (games like Taiji, or The Witness, or Portal) is because all of the puzzles are built atop an underlying system, every puzzle has the potential to teach the player something about how that system behaves, and the player can use this information to better solve new puzzles.

When there is a sequence of puzzles which are specifically designed to build up an understanding of a systemic idea in the player’s mind, this functions very similarly to a paragraph of text. (In the lecture I gave a couple years back, I referred to this concept formally as a capital-S Sequence, but whatever you call it, it’s just a smart way of structuring of a series of puzzles.) In the same way that a paragraph is a series of sentences elaborating on one shared idea, a sequence is a series of puzzles with a shared idea at their core.

So, back to pacing for systemic puzzle games. How exactly do we go about it, and can we at least draw a broad outline of what constitutes good pacing?

I would say that the ideal structure for puzzle sequences follows a dramatic arc. The beginning is marked by a slow and logical build-up, the player works through puzzles step by step, and then there is a climactic moment to cap off the sequence. This climax to the sequence can take on a lot of forms, but the first two parts are usually very similar across all sequences.

This structure shares an obvious similarity to the Three Act structure for storytelling. So, let’s just borrow that terminology in order to define it formally:

The 3-Act Structure of Puzzle Sequences

INTRO    >    BUILD-UP  >   CLIMAX

Every puzzle sequence has an main idea at its core, this is either a system or something that all of the puzzles in the sequence are “about”. For purposes of discussion, we’ll just call this The Main Idea. 

INTRO: In this act, The Main Idea is introduced in a relatively opaque, but simple way. The player solves a puzzle, or a short series of puzzles, and then they understand (or believe they understand) The Main Idea well enough to begin deductive reasoning about puzzles in the next act.

Because the player may not fully understand The Main Idea even by the end of this act, the puzzles here should be very simple and able to be solved quickly in order to not lose momentum early.

The player will be solving most of the puzzles in this act using intuition, so it is important to keep their assumptions in check and make sure they don’t get lost in the weeds. This is a particularly good time to use Reprises (when the structures of two puzzles are very nearly identical, in order to emphasize the differences) to create counterpoints to certain wrongheaded assumptions and build understanding.

BUILD-UP: In the second act of the sequence, The Main Idea is explored more deeply, with various puzzles gently increasing the challenge or layering on complexity.

Puzzles in this section are less intuitive, and require the player to use a more top-down approach, deducing the solutions based on what they have learned in the first act. Momentum is ideally constant or very gradually decreased during this part, with each puzzle taking about the same amount of time as the one before it.

CLIMAX: In the final act, we finish exploring The Main Idea, and the puzzles reach their highest point of challenge as the sequence ends.

Sometimes the most satisfying way to conclude the sequence is by introducing a twist. This is a puzzle which must be solved through lateral thinking rather than deduction. There is something that the player does not know which is required to understand and solve the puzzle. Optionally, this knowledge can redefine or re-contextualize The Main Idea. If this happens, when we proceed to the next sequence, it will be with the same Main Idea, but with the new context.

Pacing in this final act is less important, and the puzzles can be very difficult and time-consuming here. As a rule though, the final puzzle in the sequence should take longer than the ones that came before it.

(Additionally, it is useful to remember that a larger area which explores one Main Idea can be built up out of multiple sequences. To reprise the literature metaphor, the larger area would be similar to a chapter in a book, where the sequences would be paragraphs, and the individual puzzles, the sentences. In this case, each sequence will usually explore a small aspect of the overall Main Idea, and the structure of the full area will have an arc of increasing difficulty that is somewhat similar to the individual sequence, although not as rigid.)

The best sequences are generally the ones which hit the main points of each of the acts very clearly and without losing player momentum at the wrong times. Ideally the overall pace should start quickly and slow as the sequence progresses, with the easiest puzzles being in the Intro stage, and the hardest and most time-consuming puzzles being the Climax to the sequence.

Ideally we want to think about pacing as controlling the difficulty of the puzzles over time, but evaluating the difficulty of any given puzzle is not straightforward. In fact, it is one of the more subjective things in the entire field of game design. Although the skills developed by playing one action game oftentimes carry over to the next, this is rarely the case with puzzle games, and the perceived challenge of any given puzzle can vary quite dramatically between individual players. There is some correlation between higher IQ and lower perceived difficulty of puzzles, but there is still enough variation in the ways in which people think that some difficulty spikes are probably unavoidable.

I think this is a big reason why, perhaps more so than for other genres, it is important to have a large number of testers on the game, and to take each individual test with a grain of salt. One has to have a strong vision for what the player’s experience should be like, and also have a developed sense for when the deviations in a particular player’s experience are acceptable and when they are not.

This is more or less where my theory starts to unravel a bit. There may be a way to develop a good method for objectively evaluating puzzle sequences, but I see this as one of the areas where it is still more art than science. Even with infinite time and good luck, when making puzzle games, one must always accept that a certain number of players will have a bad experience. Really the best you can hope for is that a greater number of players will have an experience that is closer to the ideal than those that do not.

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I’d like to close with a quote from Italo Calvino’s Invisible Cities. I didn’t really find a way to work it into the essay naturally, but it resonates with me in relation to the type of puzzle game design that I do. It comes from a chapter in the book which is sort of acting as a meta-commentary for the whole book. For context: the structure of Invisible Cities is a series of descriptions of the ways in which a city might be constructed. However, there are some descriptions which are more valid than others:

“…from the number of imaginable cities we must exclude those whose elements are assembled without a connecting thread, an inner rule, a perspective, a discourse. With cities, it is as with dreams: everything imaginable can be dreamed, but even the most unexpected dream is a rebus that conceals a desire or, its reverse, a fear. Cities, like dreams, are made of desires and fears, even if the thread of their discourse is secret, their rules are absurd, their perspectives deceitful, and everything conceals something else.”

“Invisible Cities” – Italo Calvino