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Practical Game Design : The Rule of Threes
by Lars Doucet on 03/04/10 03:00:00 pm   Expert Blogs   Featured Blogs

The following blog post, unless otherwise noted, was written by a member of Gamasutra’s community.
The thoughts and opinions expressed are those of the writer and not Gamasutra or its parent company.

 

 

 

The Three Amigos! starring Steve Martin, Chevy Chase, and Martin  
Short

 

This is the first article in a series I'm calling Practical Game Design.


The idea is to look back on the great masters of game design over the past few decades and extract some useful techniques from their games that we can immediately use in our own. I'll stick to specific examples as much as possible.

The first one comes from Shigeru Miyamoto himself, and although it might be known by other names, I'm going to call it "The Rule of Threes." This is a practical level design technique that introduces the player to new challenges gradually.

Here's how it works:
 
 Before you challenge the player with a new feature, you first present it in 3 easy but varied situations.

This technique is a favorite of Shigeru Miyamoto, and really helped differentiate his games from all the other punishingly difficult NES titles of the 1980's. This technique does not makes your games "easier," however.  Instead, it makes your games more "learnable" by making sure that the player has been "primed" before the real challenges begin. The best part is, you don't do this with boring, pedantic tutorials. You just do it with gameplay. As Raph Koster would say, the player learns by having fun.

Since this is Practical Game Design, I'll explain the technique through example. Let's take a look at the original Super Mario Bros. and see how the Goomba is introduced.

Super Mario Bros: World 1-1: A goomba approaches from the right

 Step 1: Introduce the Challenge as simply as possible

 

The first time we ever see the Goomba, he's just walking straight towards us. No tricks, nothing fancy: there's just one of them and he just slowly lumbers in our direction.

Note that this is the easiest possible way to challenge the player with a Goomba.

For most of us, this isn't much of a problem. Stomp him or hop over him, and you're good. But, back in 1986, this being the first video game many people had ever played, many players would have been killed by that first Goomba. But that's no big deal - one life down and start from the beginning, no progress lost. Try again.

Note also that it is literally impossible to get past the first Goomba without learning the game's most fundamental skill: jumping. This means that the game designer can assume that any player that gets past this initial point knows how to jump.

 

 

With this challenge, the designer tells the player:
"There is such a thing as a Goomba."
 

Okay, first Goomba has been jumped over. Move to the right a bit, and here we see our second Goomba.

Super Mario Bros. World 1-1: a goomba between two pipes

Step 2: Do it again, with a slight variation
 


He's bouncing back and forth between two pipes, and we are standing on a pipe.

This is one step up from the easiest possible Goomba challenge. More importantly, however, this shows us a new dimension to the Goomba. Before the player needed to merely stomp the Goomba or jump and let it pass. Now we have a different situation: it will bounce back and forth when it hits a pipe. The confined space changes the nature of the challenge.

 

With this challenge, the designer tells the player:
"The land around the Goomba can take different shapes"
 

This one isn't particularly difficult, either, and the player is likely to get past this stage fairly quickly. As soon as the player is past this point, the designer can assume the player has absorbed his first two lessons.

Next, we see this:

Super Mario Bros. World 1-1: two goombas between two pipes.

Step 3: Do it again, with another twist
 
 
A variation on the challenge we were just given, here is a wider span of two pipes, with two goombas moving back and forth together.

This one is interesting, because it's both easier and harder than the last challenge. It's easier because there's more space, and because you can stomp both Goombas at once, and harder because there's twice as many of them, so that even if you get one, you might still die.


With this challenge, the designer tells the player:
"The Goomba will not always come alone."
 

It only takes about 10 seconds to make it through these three challenges, but already the player has been given a very good introduction on the game's first enemy type. We've learned the basic skill we need to deal with it (jumping), and we've been given a quick but representative sample of the various situations in which Goombas will be thrown at us.

 This might seem a bit simplistic, but there are plenty of games in which the player is not properly "primed" for new challenges before they're presented. Instead, the player's first encounter with the new challenge is to be beaten in the face with it unexpectedly. Not only is this frustrating, but the player is unlikely to learn much from this scenario. The Rule of Threes is a great solution to this problem.

So, back to Super Mario Bros. Now that Miyamoto has introduced us to the Goomba, what happens next?

 

Super Mario Bros. World 1-1: Goombas from the sky!
 
Step 4: NOW let 'em have it!

  
Here we have Goombas falling off of ledges and threatening the player from above. This is really the first time in the game where Goombas are presented as a challenging threat. Imagine if this was the first thing that greeted you upon playing the game. Sure, plenty of us hard-core gamers with decades of experience today would have no problem with it, but as a 5 year old in 1989, I can imagine being plenty frustrated. That simple 10-second build up of gameplay really helped prime me for this situation back then, and it will work the same way for players today.

This is what's really important about level progression. In essence, you're building a learning curriculum for the player. You present the challenges in isolation before you ramp things up, so the player learns individual skills first, which can be layered together into more complex skills later.

The Rule of Threes can be used across many scales, both in and out of levels themselves. Each world in Super Mario Bros. consists of 3 preliminary levels, and then a challenging "castle" level, after all. In this way the Rule of Threes is applied throughout the structure of Super Mario Bros., kind of like a fractal.

 Just look at the last corridor of the first castle, before you meet Koopa for the first time:

 

 

Super Mario Bros. World 1-4: Fireballs approach the player before dealing with Bowser.

 The Rule of Threes in action: Preparing the player for Koopa

 

Rather than just let the player deal with Koopa and meet instant death, the player is given a short training course on fireballs. First, a fireball comes straight at you in isolation. Then, the terrain changes and the fireballs come at different heights. Finally, the fireballs start to come more quickly. The player has been "primed" for battling Koopa before the fight has even begun.

Obviously, there's nothing magical about the number three. I picked it as it seems like a nice rule of thumb - once you've shown something to the player a minimum of three times in different situations, you can start to mix it up without being completely unfair. 

There's plenty of other useful techniques and interesting structural lessons to be learned here, but I'll just keep this short for now and leave those for future posts.

Let me know what you think! Is this helpful to anybody?


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Comments


Alan Rimkeit
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I like it. It seems like a good system and it makes sense to me both from a design stand point and mathematically. Three is just a good number. It also explains one of the reasons why SMB was so successful back in the day.



Also, super WIN for the Three Amigos pic at the top. You got a huge laugh out of me immediately! Good times man, good times. ;)

J Spartan
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Very nice article Lars, and you can never have too many about good game design prinicples. So please carry on.

Rafael Vazquez
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Good post, 3 does seem a good number for teaching someone something new. With a little bit of creative design, the player won't even notice the number. I wonder, if the gameplay twist is too big, would it still work, or should we let the player in more slowly, maybe giving him 5 chances to taste what lies ahead.

Dana Fortier
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I hadn't even realized this was a nintendo thing.



Be careful with your terminology, this shouldn't be a rule, but more a philosophy for introducing new enemies/strategies/platform types/whatever to the player. Don't get hung up on the number or the idea that the player should never be surprised by new interaction types.

Kumar Daryanani
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Very nice write-up! Small practical lessons like these are a great resource, thanks for writing it and sharing it!

E Zachary Knight
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One thing I recall in playing the Metorid games is the way they give the player a new peice of equipment to use.



Upon getting the new equipment, let's say the Morphball in the beginning, the player is shown through the game what the item does. In this case upon getting the morphball Samus turns into the ball to demonstrate it. Next the player must use the new item in a non threatening way to get back out. In the case of the Morphball, the player must use it to roll under the rock ledge that is too high to jump. From then on, they know how to use it to get past obstacles. The same thing happens with everything else as well.



The key is to introduce the player to new gameplay concepts in as nonthreatening a way as possible while still allowing them to be challenged.

Lars Doucet
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Thanks, everybody! Do you want to see more of these little practical "rules?"



@Dana:



I use "rule" as in "rule of thumb." We might just be quibbling over semantics here, but for me the existence of a rule implies that those same rules can and should be broken in certain cases. That's why I called it the "rule" of threes instead of the "law" of threes, for instance.



There is of course nothing special about the number 3, it's just a useful minimum, and I can imagine plenty of cases where you'd want to throw something completely unexpected at the player and dispense with this "rule" altogether. But as far as practical game design tricks, I think it's useful for most cases.

Tim Tavernier
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I like this article just for the fact you use Shigeru Miyamoto. I think he gets neglected too much as the living breathing supercourse on "How to Make VideoGames Fun and Challenging For Everyone" that he frankly is. Someone could really write a entire book on Practical Game Design on this guy, and someone should actually...



That said, it is a really good structural and practical analysis of how you can ease in people into games.



But I would like to add another layer, that of player experience. What Shigeru Miyamoto (on a player experience level, you described the Game-Design level marvelous) actually did was teaching the player as fast and simple as possible the possibilities of how the player can "kick-ass" inside the game without being "ass-kicked" too much from the start.

Another thing Miyamoto did was also introduce the games' Universe premise in a again simple but very effective way. It's 1985, you're 6 years old, you play this game, you see the Goomba slogging at you "what is this, a walking mushroom?? Questions boxes?? Mushrooms for me? Pipes? What kind of universe is this? Man this looks like fun!" And with every world, Miyamoto adds to the Wonderland-experience.



The point i'm trying to make is that this article described wonderfully how Miyamoto introduced players in a non-threathening way to the rules of the Playfield of this game. But at the same time he also, in a very simple additive way, introduces the people to the engaging Universe of the game. So not only mechanics but also world, fantasy, story. Super Mario Bros wouldn't be Super Mario Bros. without both aspects.



Just for good measure I'll repeat, My comment is meant as a addition to this great simple but highly effective analysis of Practical Game Design. I did this because mechanics is only one layer what makes videogames great, the context, the content, the universes you get to play in is another important layer in this. The true "Joy" of a Videogame is the resulting synergie when both layers collide in a wonderful mess.

Lars Doucet
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Hey Thanks, Tim!



I think you've hit on some topics I'd like to cover in some of my next articles :)

Kevin Lim
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Nice article!



Good things always come in threes.



In Comedy there's also a rule of threes. (http://en.wikipedia.org/wiki/Rule_of_three_%28writing%29)



If you look at old Tom & Jerry cartoons for example:

Tom chases Jerry around the kitchen once.

Tom chases Jerry around the kitchen one more time.

Tom chases Jerry around the kitchen but realizes Jerry's gone.



The variation will often comes at the third iteration.



I guess 3 is just a nice number people start to naturally recognize patterns, though having those 3 each be of different variations definitely helps compress these patterns & information for the player.

Sean Choate
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Hey, Lars, nice write-up. I remember talking about this with you a while back.



You did a good job presenting the idea in a concise way, and it inspired me to do some more thinking on the topic, because I believe this rule is a very important concept in game design. Nearly essential, really.



The reason it's a rule of three isn't because 3 is a magic number. It's because 3 is enough to establish a pattern, as Kevin points out.



Designing games has a lot in common with writing, because you're world-building for the player. This isn't world-building in the Tolkien sense, but in the sense that you are establishing the rules of the game in a concrete way. When you set the expectations of the player and then deliver on those (or artfully subvert them) you will, as a designer, be creating a situation where your players can have a positive experience.



Taking this to the Goomba example, at any point on the path, the player has only his own skill to blame for failure.



In the first step, the player is expected to know the controls. If you do, you should be able to jump.

In the next step, the player is expected to be a little better at jumping (or can run and jump from one pipe to the next). In the third step, you can't circumvent the challenge except with a significant running start, so you really have to not only be good at jumping, but be familiar enough with how a goomba moves that you can predict the way two will bounce off one another in order to properly time the jump.



It's after the third step that the magic happens. The player is now trained to expect goombas to bounce around on the ground. He's trained to want to jump on them from above. Putting the goomba on a ledge subverts this trained expectation in a surprising way. It challenges the player. At this point, we've got a nearly pure example of a challenge. You take an obstacle with which the player is familiar, and you present it to them from a new angle.



This is why I must respectfully disagree with Dana Fortier. There actually is something magical about the rule of threes. It's not that, as a player, I don't want you to mix things up and surprise me. It's that IT IS IMPOSSIBLE unless you, as a designer, first establish an expectation of how to interact with your world.



Then, you can subvert that expectation with a neat little twist, and your players will be delighted. If you neglect that, it's similar to a writer resorting to deus ex machina to get his hero out of tight spot. The rule of threes is essential to establishing an internal logic of interaction, just as your story needs an internal logic in order to suspend disbelief. Often, these two are tied together.



I've been playing through Mass Effect 2 again recently, and I was reminded of the first time I played through it and I made a poor choice near the end and one of my party members died. The game never prepares you for this series of several incredibly important choices in any mechanical way prior to the final mission. A designer might argue that the final mission is one where the player should feel like he or she is in uncharted territory, and I agree. I don't agree that out-of-left-field game mechanics accomplish this.

The bottom line is that Mass Effect 2's final mission choices would be far more successful at providing a sense of mechanical continuity with the rest of the game if, prior to that mission, the player was compelled to assign his or her teammates to mission-critical duties outside of the three-man squad that, for 90% of the game, makes up the entirety of player choice about the survival of one's teammates.



Since the player has no mechanical expectation for how these choices will affect the game, the deaths of his or her squadmates (via cutscene) feels more like being robbed than being fairly punished for a poor decision. The sting is lessened for subsequent playthroughs mainly because of the expectations established by the first playthrough.



So, yeah, this is even more important that the blog post makes it appear at first glance. It's not just about preparing the player for later challenges, but about establishing a coherent internal logic to your game mechanics, just as you'd do for your story.


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