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Design & Style

System Design

Will Wright

Lesson time 21:34 min

Understanding the fundamentals of system design will help you build more robust interactions in your game. Will shares his tips for what to take into account when designing an interactive system for your players.

Will Wright
Teaches Game Design and Theory
Collaboration, prototyping, playtesting. The Sims creator Will Wright breaks down his process for designing games that unleash player creativity.


Within these games, within these worlds, there are a lot of moving parts, a lot of dynamics. You want this to be a rich, interesting environment for the player to explore. My approach has always been to step back and think of this whole thing as a system. What is the system that's happening here? And actually, when you get down to the engineering of things like simulations, you really do need to think of it as a system. And you need to think about it, what is my paradigm? What is the way in which I'm going to structure the world? How is it going to operate? What are the parts? How do they interact with each other? Systems are interesting. In some sense, what they're going to lead us to is this idea that everybody in a game is going to be exploring the possibility space of that game. Where are all the possible states that that world could be in? For something like chess, it's fairly obvious, although it's a very big, branching tree. It's a branching tree. Every move in chess leads to another set of possible moves. And you unfold that branching tree of all the possible moves of chess and you come up with an astronomical number, but it's still finite. There are a finite number of possible states in chess. The very early games had very simple branching trees, very much like chess. Basically, structure branching trees that were explicitly put there by the designer. And this is very much like one of those old choose your own adventure books. If you're going to go into the cave, go to page 7. If you're going to go to the top of the hill, go to page 20. But basically, the writer's having to fill out every possible branch of that book. So it's a very limited structure, a very limited world to explore. Later games started doing what I call gated experiences, a game like, let's say, Quake or Doom. You're within a level and you have all this agency and freedom within that level, but until you get through the level and get to that locked door at the end, basically, you're in this little room, this little, small regional possibility of space. Once you get through that, it opens another regional possibility of space. So you basically have these little islands of possibility of space with gates between them. And then there have been basic hybrids of these two models over time. But then as players and designers started building more open-ended simulations, it opened up a lot more. So as we started building open-ended games-- sandbox games, Grand Theft Auto, Sims-- we're actually looking at a possibility of space that's vast, large. And this is when we really have to now view it as a system, not as a branching tree of possibility. We're not going to map out every possibility. What we're going to do is we're going to build a set of things that interact in a way to, basically, generate these possibilities for us. For the Sims, the way I visualized it was that, basically, you had two directions you could go for achievement. You go for ...

Explore the Possibility Space

Learn the art and science of game design with Will Wright, the mind behind SimCity and The Sims. In this game design class, Will teaches you how to create games that empower players and unleash their imagination. You’ll develop a tool set for understanding player psychology, as well as learn Will’s approach to generating and pitching ideas, prototyping, playtesting, and building a community.


Students give MasterClass an average rating of 4.7 out of 5 stars.

I am certainly not a video game creator, but I am an Art Director who works in the world of ideas and creating experiences. Will Wright really makes t

I really liked the whole Masterclass and it was structured very well. Thank you

As an amateur at being an amateur game developer, having some of the learned lessons passed onto me from one of the great minds of the industry is invaluable. Even if my own designs aren't about cool mechanics-- as someone with limited talents to realise those mechanics-- I think the lessons here are still quite valuable.

I enjoyed this class. I love the intelligence and openness Will brings to the game design experience.


A fellow student

Easily the most valuable module so far and likely in the course for me. I will be incorporating each of the meaningful parts of this discussion for the game I am creating into the design doc to push my understanding. @Molly E - Is there a possibility of the teachers, Will Wright, doing a video chat every once in awhile with students? This would be an amazing resource for those of us that have questions both that we know and what we don't know we have until we hear others ask the teacher. If done, I would recommend saving the chats and making them available to the students.

Dan R.

Love this module but get errors trying to download the PDF. Anyone else have issues?

Rich C.

Wonderful app! Thanks so much for providing it. (Link in workbook.) Speaking of Conway's Life, a friend and I attended one of Will's lectures at GDC--this was before Spore had been released. He was talking about similar things as he does here, including cellular automata and the Holy Grail: emergence. I had a decent Life program running on my C64 in elder days, and so was already a long time fan, so I dug what Will and his team were up to. Anyway, within minutes of leaving the lecture both my pal and I said to each other, half-jokingly, "Life shooter!" Our dimwit reaction, right. But once we figured out how to do it (to make a semi-long development story short) we made one and it worked out pretty good, even getting a couple of IGF awards (who'd a thunk?). The game is called Dr. Blob's Organism.


Super interesting how he puts different strands together. Are there any preferred tools or templates of how to model the whole system? A while ago, I had taken a dive into System Dynamics and started modelling with SD software (Vensim), but I ended up going back to Excel because it's much quicker and easier to keep track of the essentials. Are there any best practices of how to do it? For example how was the first draft of the Sim City economy/system modelled?

Victor H.

I would like to have a better example of what a Layer would be. I understand the concept of agents (having their own state) an dynamics showing how state changes in response to stimuli. I also see networks showing relationships between agents. However, what would a layer be? Would they correspond to particular types of state variables? Will mentioned pollution and crime, or are these external factors that affect our agents? (like weather wind, gravity). I'm using an ECS architecture for my game (entity-component-system), would layers map to particular types of components?

Todd H.

Is there more details about the design of sim city? I’d love to hear more about how the game of life and cybernetic theory were combined at a practical level.