Physics Games and Physics-Based Game Downloads

Here’s something different: an interview where I’m answering the questions instead of asking them. Andreas Schiffler recently interviewed me about physics games as part of his PhD research. He’s studying how society is impacted by the reproduction–sometimes incorrectly–of physics laws in video games. The interview covers a lot of ground, from specific games to more general, philosophical discussion.

It’s quite long, but I thought it was interesting enough to be posted here. Enjoy!

Andreas Schiffler: Before I start to get into the specific details, I’d like to know a bit more about your background as programmer and game developer. What did you study and where did you get your initial work experiences as game developer?

Matthew Wegner: Despite the fact that I basically do programming today, I actually went to art school (Cogswell College in Sunnyvale, CA). I ended up leaving before I finished my degree, but I did maintain close relationships with a lot of my college friends and started up my company with them 3 and a half years ago. I don’t have any formal programming or computer science training.

My initial work experience as a game developer, in the professional sense, was actually when I co-founded Flashbang Studios. We currently develop for the “casual games” market, although our goal is to eventually fund games more along the lines of the “indie” aesthetic. You know, titles that are innovative for innovation’s sake, viable markets be damned.

You mention, that you are driven by a “passion for physics-games” on the website. Did you study any physics and what was the most interesting aspect of your physics education that you remember? What about today’s physics research — anything on the radar that you are really interested in?

My last formal physics education was in high school (AP Physics in my junior year, if I recall correctly). What I remember most is the unavailable answers for such seemingly simple questions as the root cause of inertia or gravity. Complicated formulas for describing motion are all well and good, but I took issue with the notion of terming such things as “laws” of physics. They’re merely descriptions, not the underlying mechanisms. There was a lot of falling back to, “because that’s the way things are”.

To be honest I don’t keep a very close ear to the ground for modern physics research. I’m dimly aware of the directions that things like quantum mechanics are taking, but the psychological ramifications of an observer-centric world are more interesting to me than the underlying mathematical ramifications.

You have been involved in the gaming industry for a while, I presume. In very general terms, what do you think of todays games and game platforms? Where are we headed?

I’m actually fairly young (26), so I don’t have the depth of experience of a lot of my peers in the industry. I have played games all my life, though, and tried to become more aware of the processes behind their development when I was younger.

Professionally I’ve been focused on casual games for the past three years, so that gives me a much different perspective from a retail game developer. It’s kind of depressing to see how retail development is still focusing on the same market segments and genres of games as it did ten years ago. But then again the casual market has emerged with the same fixation on standard genres, so perhaps that’s the inevitability of the dollar.

Platform-wise I think games will diversify from 50-hour, high-production experiences to a wider range of experiences and time investments. It’s already happening now, but I think the trend will continue. It’s the difference between eating once a day and snacking continuously.

Culturally the notion of “gaming” and “gamers” will dilute to the point where games are viewed in the same way that mainstream entertainment is today. Particularly in the casual market, there is constant discourse identifying the “casual gamer” (typically the 35 year-old soccer mom). Other media don’t distinguish like this–there isn’t such a thing as “causal books” or “casual movies”. Everyone participates in those kinds of entertainment.

How do you think mathematics, engineering and physics is perceived today by the general public? Is there a need to educate more in this area? If so, why?

I think mathematics, engineering, physics, and other scientific disciplines are viewed by the general public as Black Magic. Seriously. I doubt the average American has a clue as to how their TV, microwave, or car works. The complexity of objects in our day-to-day lives dictates that, though. I would consider myself a fairly advanced computer user, but even then I don’t know anything about designing silicon or the process involved in fabricating integrated circuits. There’s no way I can understand the operation of every device that allowed you to use a computer to email me this interview.

But I don’t think the issue is one of knowledge. There’s simply too much information in the world today for any one personal to comprehend even a fraction of it. The issue is how well the general public understands the principles behind that knowledge (the scientific method, I suppose). Society is certainly lacking in that regard.

Is there a need to improve it, though? I guess it depends how you define need. It isn’t required for society to function. A general improvement in critical thinking could result in increased efficiency across the board, I suppose, but I don’t think it’s a requirement. That’s the nature of technology. We don’t necessarily need to understand something to benefit from it.

Now, I’d like to ask some questions related to your website fun-motion.com which features the extensive analysis of physics (or its simulation) in games as part of a selection and review process.

With what game did you get started on the website (i.e. your first review)?

Well, the first game I actually posted on the site was one of my own projects, Amoeball.

The game that inspired me to create the site in the first place, though, was Ski Stunt Simulator. I found the game immensely fascinating and wanted to share it with others (and discover more like it).

How many games did you review so far and how many games are in the “review-queue” at the moment? What’s the best game you’ve seen so far?

Currently the site has 42 game reviews. I have another 22 games to cover in my notes, although I’m discovering new ones all the time. I’m planning a “classic physics game” series, too, which will add to the total. I expect the site to easily hit 100 reviews.

How do you approach a review and what do you look for in terms of the game-physics or simulation aspect? Do you ever “measure” the accuracy of the physics (i.e. by analyzing screenshots) to verify the implementation?

My reviews have actually evolved over the months, at least in terms of length and formatting. The later reviews are all pretty standardized. In terms of content I try to avoid the trap of merely describing the game. It’s difficult to cogently analyze something to provide an insight. For instance, in the recent The Blob game review I focused on the disconnect between the underlying physics simulation and the player’s mental model of that simulation.

I do talk about the fidelity of the physics simulation, although not necessarily to “verify” the real-world accuracy of its implementation. Real-world simulation isn’t desirable in many games. We are talking about entertainment, after all. Something like FlatOut 2 is deliberately tuned to be “arcade” like in its controls. It’s impossible to control a car at 140mph through narrow dirt tracks, but FlatOut allows that experience, and they do it in such a way as to only just barely enable the player to pull it off. The deliberately inaccurate physics make the player feel like they’re a much better driver than they really would be in real-world circumstances.

Other games have less obvious parallels to real-world physics. Consider Gish. It behaves in a physical way, but without any direct real-world counterpart. Scale is completely ambiguous, as are the materials of his world. He’s roughly gelatinous, sure, but without real-world reference points it’s hard to judge the accuracy of its physics. I think games like Gish that utilize our understanding of how real physical objects behave, but through fantastic settings, have the most promise in terms of physics-based game design. It allows more suspension of disbelief, too. You can’t say that Gish is behaving improperly, but you could say that a car is behaving improperly.

People can suggest games for you to review. Do you have many rejects from these suggestions? Assuming you had some “rejects”, can you give me an example title and explain why you didn’t regard it as “physics game”?

My definition of a physics game is fairly discretionary. Most video games have spatial and physical elements to them. For instance, the original Super Mario Brothers has highly abstract implementations of collisions, inertia, and gravity. Very few games are solely about raw numerical relationships without some element of spatial relationships.

So my definition of a physics game is, “a game where the player primarily interacts with the mechanics of a complex physics system”. What I typically focus on is how complex the physics system is. I’ve had a lot of suggestions for games that are too simplistic in their physics implementation, or simply too uninteresting (i.e. a standard racing title).

And to be honest I let my personal bias dictate a lot of my decisions. I would rather focus on an independently-produced unknown title than a big-budget flight simulator. I respect risky innovation that isn’t necessarily out there to make a buck.

Sometimes I just don’t understand the appeal, though. Elasto Mania is a hugely popular game. I get a constant stream of emails asking me if I’ve heard of it or why I haven’t reviewed it. I just don’t understand what’s so fun about it. The physics are very abstracted in what I feel is a very undesirable way. I need to review it at some point to better understand why the damn thing is so popular, but I can’t bring myself to play it for more than a few minutes.

You categorize physics-games into games that focus on “Real-World Activities” and ones that implement “Abstracted Activities”. Could you provide an approximate ratio for these two categories based on the games you reviewed?

It’s kind of a sliding scale between real-world and totally abstracted, but I would say my reviews feature both about equally. I guess it depends how you define realistic, real-world activities. There are games that have stricter adherence to physical properties but in an abstract environment (take Switchball for example). It’s abstracted, because you can’t really control a ball like that in real life. If you could, though, that’s how it would behave. There is a definite sense of scale and material.

Do you have any stories, examples or even some source code that illustrates how difficult it can be to implement a proper physics simulation?

I guess it depends if you’re talking about implementing the physics simulation itself or if you’re talking about implementing a game on top of that simulation. There are dozens of papers on physics simulation available, as well as some very robust pre-built engines. Personally I have no interest in the mathematics of physics simulation, though.

As for implementing a game, it’s always a tricky balance between enabling the player to manifest their intentions in the game and adhering to the guidelines or reality. Nobody wants a game that mimics reality 100%. That’s what reality is for.

I have a good example. I wanted to implement a jetpack physics test with a standard two thumb stick game pad. In my mind, the left thumb stick controlled the left thruster, and the right thumb stick controlled the right thruster. This combination would allow any degree of movement. It took about an hour to rig up, and I was excited to try it out. In my mind I was performing amazing stunts with the greatest of ease.

What happened, though, was that as soon as I took off the jetpack invariably spun out of control. I could hover for a few seconds, maybe, if I was very careful to maintain my thrusters’ direction. It was just impossible to fly around with any degree of control.

And that makes sense, really. If you were to build a real jetpack with two rotating nozzles as thrusters it would be absolutely un-flyable. You’d kill yourself. The solution in my physics test was to apply some arbitrary impulses and torques to my jetpack to artificially force it upright. I could tweak these numbers to gradually remove stability from the point where it felt “cheap” to the point where it was fun and player skill was required.

Modern aviation does the same thing, really. Most jets, especially aerodynamically-unsound stealth bombers, have fly-by-wire systems. The computer does most of the real adjustment; the pilot loses 1-to-1 control of the system. In games it’s just a lot easier to apply arbitrary forces than it is to calculate what the stabilizing forces should be (and the player’s mental model of both systems will be identical, so why waste time).

The game “The Incredible Machine” (TIM) had an engine that “does not use a random number generator in its simulation of physics, assuring that the results for any given ‘machine’ are reproducible”. Why do you think it was designed that way? What about other games that you have reviewed — what percentage would you say, can simulate reproducably?

I would venture to say that it was designed that way. A deterministic physics system is required for some genres. Bridge Builder and Armadillo Run are good examples. The physics for any particular level or solution will play out the same way every time. It’s a requirement of the game’s puzzle-oriented design. This allows players to compete fairly against each other–your solution will perform the same on someone else’s computer. Optimization is no longer about chance but about changing your structural design.

Other games use deterministic physics in order to synchronize multiplayer experiences.

I’m not sure what the percentages would be. Any single-player game that uses physics predominately for visual effects is probably not deterministic. It’s impossible to tell with highly-interactive systems anyway (particularly when time is involved, since the player hitting a button 3ms later will have a different outcome).

Could any of the games you have reviewed be used to perform real science? If so, do you have any suggestions or examples of how this might be done? Was there any feedback regarding your website from outside the gaming community (i.e. schools, universities or artists for example)?

I don’t think many of the titles I review have much capacity outside the scope of entertainment. Some do, though. A game like Bridge Builder could certainly teach someone about the basics of structural integrity, and it’s certainly less messy than gluing a bunch of toothpicks together.

As for “real” science in the sense of cutting-edge progress, I really doubt it. I would imagine the computation required for truly meaningful simulation is outside the scope of real-time environments. It’s my understanding that using computational models for experiments is becoming very predominant in science today. I just don’t think the level of simulation in games is useful for anything except psychological experiments.

In your FAQ, you state: “My personal definition of a physics game is a game where the player primarily interacts with the mechanics of a complex physics system.” This focus on physics as dynamics is also reflected in your sites domain name (“motion”). This is understandable, since most games’ notion of physics IS dynamics. Can you give any examples of games which are not centered around dynamics/motion?

Some of the games I’ve reviewed are more about structural engineering. Armadillo Run and Bridge Builder are still simulated using mass-spring systems, but the player is internally digesting the tension of the springs as structural integrity of the material. Operation Cleaner 2 is also more focused on the properties of materials at rest.

That’s probably not quite what you’re looking for, though, since all three of those games still make heavy use of motion to communicate their physical status. I can’t think of any games that primarily focus on something else.

If you were give the task to implement elements into a game from other fields of physics such as nuclear-physics or electrodynamics, what elements would you add? Which field of physics do you think is the hardest to use as a game element?

Any element of physics that operates on a significantly different scale or mechanism than physical reality as experienced by humans is probably difficult. I think astrophysics would be easy to translate into game form, as an exception. Anything microscopic is probably much more abstract. Particle physics would probably be the most difficult to utilize in a meaningful way.

Let me point your attention briefly to the recent development in the gaming industry to incorporate physics acceleration into games (i.e. AGEIA).

Have you seen any of the current crop of “physics-accelerated” games? What do you think of them? Do you think these devices help the game designers in creating better games? If you think they do, how do they do that and or why are the games better?

I have seen the games, although I haven’t had the chance to actually sit down with PhysX hardware and play the current titles (I’m on a list with AGEIA to get review hardware, although I’m not sure they take me seriously). I think hardware-accelerated physics is a promising development. Years ago I had thought there was an opportunity for such a thing (hell, I remember when adding dedicated hardware like a SoundBlaster was a weird thing).

Better games? That’s a very broad statement. It’s like asking if a new paintbrush will help artists paint better pictures. I think there’s an opportunity there for designers to make their worlds more physically coherent. Rather than worlds where some objects are physically interactive, and some aren’t, there’s the possibility of creating worlds where everything is physical. That’s an exciting jump.

Creating more realistic worlds isn’t a viable goal in itself, though. Let’s say we get the point where we’re simulating reality to an indistinguishable degree. What then, though? We’d still need to build a game on top of it.

Manipulating perception is already more important than simulation at this point. If the goal of a game designer is to create the experience of racing a car, you don’t necessarily need to calculate wind shear (although there are games that attempt to do this). Shaking the camera as a car whips past is good enough. The player will assume the camera shake was wind blast; you don’t need to simulate the fluid dynamics of the surrounding air. And, really, if you did simulate it–and the effect was identical to a cheap hack–then it’s pointless. It doesn’t matter if the numbers inside a computer are correct or not. It matters if the experience inside a player’s head is correct.

In terms of practicality, I don’t think the current crop of hardware-accelerated physics will mean much for actual game design. Developers can’t require the hardware yet, so current usage is visual embellishment. Until we reach a point where designers can safely target consumers that must have hardware accelerated physics to play the game it won’t help design one bit.

There’s a hot concept called “stealth education” that says it’s possible for people to play a game because they enjoy it and “accidentally” learn stuff along the way (i.e. Teaching not as obvious or targeted as in “edutainment”). Unfortunately, the concept has yet to prove its worth with the pre-teen and teen community. So, on this concept there are a few questions:

Do any of the games you reviewd have a “stealth education” agenda and are there any commercial game titles available today that you are aware of, that implement this concept for physics?

Some of the games I’ve reviewed will enhance someone’s understanding of physics, sure. But in terms of the developer intending to do so with an agenda of education in mind? None that I’m aware of. There are some websites that have little Flash games to illustrate physics concepts, but I don’t know of any commercial, retail games with an educational agenda.

How would you judge the commercial potential for “stealth educational” games for the gaming industry of today?

I definitely think the potential is there. Games today are remarkably complex. Even something as seemingly trite as an action shooter requires the player learn and keep track a lot of very complicated concepts. The player is certainly capable of digesting advanced material.

I guess it depends what the educational payload for a stealth game is. Teaching world history would be easy (Civilization 4 with more accurate information and fixed timelines would work). If your payload was differential calculus, though, you might have a more difficult time. There are some small Flash games that have very specific political messages as payload that could be considered successful (September 12th for an example).

As an historical example of a game with some teaching potential, the early Atari game “Lunar Lander” comes to mind. Would you consider such a game “educational”? If yes, in which way? If no, why not?

Sure, I’d consider it educational. Games help players develop mentally, and sometimes teach them more about the world they live in. I guess it depends which denotation of “education” you’re relying on.

Do you have any examples of games that try, but fail in educating? What are the reasons for the failure?

I don’t have any examples offhand, but I’ve seen some games that are too overt in their payloads and end up sounding preachy (particularly religious titles). I think stealth education games need to keep in mind that they should be entertaining games first and foremost.

Now, I’d like to broaden the topic to some more philosophical ideas in game design.

Game developers today recognize the importance of proper physics simulations for interactivity when creating an immersive virtual world. How would you rate the importance of game physics versus graphics & sound, social constructs & story line, or other gaming elements for creating this “immersion”?

Physics are extremely important. Or, more specifically, the sensation of virtual kinesthesia is. A lot of time is spent tuning a control mechanic so that it simply “feels” better. Look at a lot of the old 8-bit Nintendo games. Mario doesn’t come to an instant halt when the player lets off the button. He glides to a stop. Old racing games have similar simplified abstractions of concepts like inertia, gravity, and friction.

What’s interesting is that two racing games (or two platform games, whatever) can have different qualities of control. One game could simply feel better than the second. And the difference isn’t necessarily one of realism–adding more accurate simulation doesn’t make a control feel better to the player. It’s a subjective thing. In fact, sometimes dedication to realism isn’t the right solution. It’s a lot like traditional animation with squash and stretch and the like.

I think physics has made a stronger push towards more realism, though. Gamers today expect interactive avatar-based environments to have reasonable physics. They want crates to push around, explosions to impact nearby objects, and so on. I don’t think you need flawless underlying simulation, though. To draw parallels with the push towards realism in graphics, you simply need to create the illusion and perception of something. A texture of grass substitutes each individual blade, and with physics simplified rigid bodies substitute complex destructible objects. In the player’s head, though, they see real grass and real objects.

Assuming we had a game that implements some basic laws of physics for its gameplay — say a submarine shooter. What would you think about a “reality” slider for the game that would allow smooth control from “arcade physics” to “real physics” similar to adjusting the sound volume? Would players use it and would it teach them something about the world?

That’s a good question, and I’m not sure how many players would use it. I guess it depends on the game and the incentives for using it. Is it entertaining to use? Are they rewarded appropriately with the increase in realism?

Some racing games do give the player the choice in fidelity of physics simulation. Usually it turns on/off forces that artificially help the car stay upright, turn easier without as much friction loss, and so on.

I think more realistic physics would teach them something about the world, but I also think that simplified abstract physics teach the player something about the world. Players could compare the realistic physics in the game to the simplified physics in the game, but they’re already doing those sorts of comparisons. Even simple physics are still viewed in the context of reality’s physics. There’s always that point of comparison; motion is something we’re substantially attuned to.

Spatiality is the main characteristics of most computer games in that they are mainly concerned with the representation an negotiation of space. Do you agree with this assertion? Could this preoccupation of spatiality in games (especially 3D games) be an important reason, why only a limited number of physics-fields (mostly dynamics and optics) are used in modern computer games?

I think spatial relationships and dynamics are predominant in games because they are predominant in life. We are physical beings, after all. The nature of motion is remarkably intuitive to all animals, so I think it makes sense that it’s a very easy thing to build inside simulations (as a random aside, we had chickens growing up–and they would predicatively track the parabolas of rocks or insects you threw to them…even chickens understand dynamics).

Very few games make zero use of spatial relationships or dynamics. Even games that are largely about numbers have some spatial significance (a game like Civilization, devoid of dynamics, still makes heavy use of distances). As humans we like turning raw numbers into spatial relationships: pie charts, bar graphs, whatever.

So it is a preoccupation, I guess, but a natural one. If we were subatomic creatures I would suppose our creations would reflect that.

One of the weakness of computers that is specifically apparent for games in their limited I/O capability — usually relegated to keyboard and mouse or a gamepad for input. Do you think that the design of the physical interfaces might be an interesting advance for computer games from an educational point of view?

I think the Wii’s controller is a good step towards more intuitively enabling physical controls. I’d love to fiddle with high-end haptic devices sometime, although I doubt the market will ever be able to support the cost of them for entertainment purposes.

To make games “better” and more innovative, do you think artistic game developers should have more scientific knowledge? Or do computer science graduates working on games need more artistic training and exposure?

Both? I do think that game developers need more education outside of learning trade skills. This isn’t just related to scientific knowledge; I’ve seen many developers limit their creative influences to other games. It’s a terrible way to get inspiration.

One way to make games more innovative is simply to have more people that haven’t been making games–or been thinking about making games their whole life–give it a try. I think technology will start to really enable this over the next few decades. Even now tools like Flash are enabling average people to crudely communicate in interactive media. Tools will be able to magnify their efforts so that the ability to express yourself interactively will be as commonplace as the ability to use your cell phone or start a blog is today.

It is fair to say that computer games ARE very influential in our society (i.e. in terms of money, the game industry is bigger than film and music together). Is there an effect on society? Is that a positive or negative effect? Are games in their effect on society similar to — say — movies and can they distort the users view on reality?

Actually, game sales only surpass box office movie ticket sales. Movies still win if you consider rentals, DVD sales, and so on.

I think video games are as influential as any other media: books, movies, television, and so on.

Real-world human relationships don’t operate the same in media as they do in the real world. But, I think the exposure to a wide variety of relationships (realistic, contrived, or otherwise) broadens our understanding of emotions in general. An interesting question is this–does reading/watching media about human relationships better equip me emotionally to deal with real relationships? Can a poorly-written movie still provide insight into my own relationships? I think games act in a similar way with regards to physics and the nature of reality.

As for positive or negative, I think the argument that video games are a complex form of entertainment, and therefore aid cognitive development, is a very valid one.

To finish off, I’d like to ask you a few questions that came up during my first session of our PhD workgroup — I just wanted to hear how you would answer them (if you have anything to comment on these at all).

Folk Physics is best suited to cope with the kinds of objects and events that we encounter on a day-to-day basis and is not really designed to provide accurate descriptions or explanations of the universe. Do you think it is possible that game physics will “teach” some form of folk physics to the players? Could this have any negative side-effects?

I think some games will actually help players unlearn folk physics. Take the Battlefield franchise (7 million units sold). The game has several physics models for various craft: airplanes, tanks, boats, etc. Players need to do thing like take the speed of their vehicles into account when they fire missiles or drop bombs. Things don’t fall straight down, a classic example naïve physics.

I guess it depends on the game, though. Some games will have a very simplified physics model, while others could teach such interesting concepts as planetary motion. Players are more likely to experiment inside the bounds of a game’s physics engine, too. They very quickly explore the possibility space. That kind of experimentation is beneficial to learning. I think humans tend to do the same kind of exploration as babies (chew on things, throw toys, generally figure out how physical reality operates), but as teenagers or adults we kind of give up on that. Games are a good outlet for continued experimentation.

What is the advantage/difference of a physic games compared to the real physic experience (i.e. in an experiment)?

The question implicitly addresses one major advantage. The artificial physics experience is malleable. That affords a lot of control in designing experiments, particularly those aimed at player behavior.

Physics games are probably just as well suited as reality for any experiments regarding human behavior and psychology. You could get someone drunk and have them play a racing game to learn about reaction time and drunk driving (without needing to put them on a real road with a real car).

You use the word experience, too. I don’t think it’s that difficult to get the experience of reality and the experience of a physics game to match up. Users play a game in their head. They aren’t privy to the raw numbers inside the silicon. Rather, they take cues from the game to build their own mental model of how that world is operating. This model drives the experience, not the game. Oftentimes our mental models of a world are much more complex than the underlying simulation, so the experience is more identical to a real-world experience than the hard-and-fast simulation.

It’s interesting that the concept of folk physics is the reverse of this phenomenon.

Would it be more interesting for a game developer to use physics laws to create new games in which specific laws would have the main influence on the game (example: TIM)? Or is it more interesting to improve existing games by incorporating exact physics phenomena into the game logic (example: a modified Tetris game)?

Triptych is a good example of a “physics-y” version of a classic genre. It plays a bit like a physical version of Tetris.

I have thought that it would be an interesting experiment to craft new physical laws and then apply them to a game world. Define a basic concept like gravity in a new way, or mutate the rules of inertia (how about “an object in motion tends to accelerate?”). Honestly, though, I think it would be a tremendous failure. Players just wouldn’t be able to relate. The success of dynamics in games is wholly due to the fact that we experience those dynamics on a persistent, continuous basis.

Thanks for your time in answering all these questions.