Are games the most complex / impressive applications?

Short answer: No.

Long answer: Games actually aren't all that complicated. It depends on what you're talking about when you say "games" but the two contenders for most complex games would be 3D games and online games (particularly massively online games).

The complication in 3D games comes from taking a model of a world and rendering it in 3D and to have it behave in a "realistic" (within the rules of the world) way. Creating a visual and auditory environment from that isn't actually that hard. It's pretty much all linear algebra and is a mature field of computer science.

The real trick comes in making that process performant in real-time. Over the years game programmers have had to make a LOT of tradeoffs between realism and performance (eg if you can make a performance algorithm that'll generate realistic looking trees that's actually worth a lot of money). So games have naturally gotten better (visually) over the years as computing and graphics power has increased.

Now some game programmers have made real innovations in this field that have (rightly) earnt them a lot of money. John Carmack (id Software: Doom and Quake) and Tim Sweeney (Unreal) spring to mind.

The real cost however in making games is the content. Just go look at the credits for a modern FPS (first person shooter) game and you'll typically see as little as 6 programmers but there'll be 30-50+ artists. Content isn't complex (from a software point of view). It's just time consuming.

As for online games, I remember when Everquest came out and people raved about how hard it was. Bzzzt, wrong. For those (like myself) who were familiar with the development of MUDs (mutli-user dungeons) through the 90s (and possibly 80s), architecturally an Everquest server wasn't that complicated.

Same goes for World of Warcraft or any of these other games.

If you want to talk about complex, how about the Windows XP operating system these things run on which has an estimated 40 million lines of code? God knows how many Vista has. Or what about the Linux kernel?

Now in government, the military and the private sector you'll find other applications that have literally thousands of man years invested in them.

Air traffic control systems are fault tolerant, safety critical, high availability, and distributed. There is no downtime ever, the system must run 24 hours a day, 365 days a year, even during system upgrades. There isn't really anything that is terribly computationally complex (no AI for example, because you want the system to be predictable), but from a system standpoint there isn't much else that has to run at that level. Even space mission software only needs to run as long as the mission does.

I've worked a bit on the code for one of NASA's sattelite ground stations. The system's job is to electronically keep track of, and control all of NASA's satellites. It might not sound like much, but if a system crashes while you are in the middle of commanding a satellite, you can send billions of taxpayer dollars spinning into the sun. So the fault-tolerance and redundancy built into that setup would make Blizzard jealous. IIRC, there were somewhere in the neighborhood of 50 servers, the more important of which have a hot spare ready to take over in less than a second if the primary fails. Each one of those systems in turn has a redundant pair of systems ready to take over if both fail. I have yet to see any game as complicated (or impressive, in its own way) as that.

Each one of those ground stations interact with each other in realtime (both electronically, and via human interactions), along with all the sattelites themselves of course, and the shuttle when its up there, and various ground terminals that process orbital data, and could thus be considered mere parts an even larger and more complex system, which NASA calls TDRSS. Here's a very conceptual diagram I found online:

_{(source: nasa.gov)}

The "White Sands Complex" is physically located in far southern New Mexico, near Los Cruces. As you can see inside its block, there are three entire ground terminals like the one I described, all networked together and to the the sattelites. Plus there are two more remote ones (I'm not sure where they are).

Games certainly cover a very wide breadth of computing technology, from hardware optimizations to databases, AI, advanced maths, you name it.

It's hard to establish a benchmark for complexity, I'm not sure if any actually exists. If you think about it, things that are trivial to us today were really hard problems to solve just a handful of years ago, so complexity is a moving target and we're all building on top of it.

If we had to analyse what is involved in just reading your question, the vastness of the problems to solve are staggering: imagine the complexity of the software that were used to manufacture the electronic components for your machine, my machine and all the other machines in between.
Imagine the amount of complexity involved in getting computers to pass around information to each-other reliably.
Imagine what it took for the OS to manage all this hardware, for the browsers to evolve to the point where they can display complex layout information on screen...
All this is staggering to me.

You could point to a particularly complex application, but if you think about it, there is probably always another one that looks simple enough on the surface but can be viewed as even more complex when you take everything into account.

I would say a definite no.

Modern games are certainly impressive, though their software and hardware technology lags significantly behind the state of the art in the academia, industry, and military. After all, they are meant to run on common enough home hardware. I am sure that the military trains their people on more realistic simulations.

From a computational standpoint, games are not that interesting either. Modern games (e.g., Fallout 3, GTA4) certainly seem amazing because of their "opened world" and extremely long story, but that has nothing to do with technology, but rather with production value. Popular games now require a larger cast and investment than some Hollywood movies. So sure, you have a model of New York rather than a block, but so what?

Even MMORPGS are not that impressive. Yes, they have many interacting agents. However, enterprise applications that include automated agents have way more agents, operate faster, and have higher reliability requirements.

Finally, I would say that with the exception of cutting-edge algorithms that are tested out using games such as chess since these serve as benchmarks, game AI is not that advanced. Again, the military (and financial companies) have much smarter applications.

Take a look at some of the physics applications developed by the Department of Energy:

• http://www.scidac.gov/

There are applications there that do:

• climate simulations
• fusion energy
• molecular dynamics
• fluid dynamics
• quantum chromodynamics.

These are some of the most computationally intensive problems that exist, and millions of CPU hours are devoted to them every year at various supercomputing centers. These are highly parallel codes, and understanding the physics and how to map it efficiently to networks and processors (e.g. with MPI) is tremendously complex.

Machines with millions of cores are expected by 2012 to run some of these things.

Games aren't all that impressive from a complexity viewpoint. I assume you were thinking FPS-style games which certainly wow with their graphics capability. As far as computation goes, they certainly do a lot but it's mostly just a lot of tried and proven algorithms running on ever-increasing numbers of polygons and higher resolution texture maps.

Simulating a physical environment isn't all that hard either; provided you want the environment to obey the known laws of physics because most of that stuff is somewhat basic and well understood.

The Mars rover missions are an impressive feat. No dynamic memory allocation, debugging the code while it was running, on Mars, and uploading a fix for a bug, on the fly. In terms of robustness, I'd say that comes close to taking the cake.

I'll tell you what I think is most unique about game programs, and what to me makes them maybe the most impressive...is how bugs affect the overall produce. If you have a bug in say, Outlook (hah), there are a couple different ways to address it (I'm going to oversimplify here):

1. Fix the bug.
2. Give the user a workaround, if there's another way to accomplish the same thing.
3. Just leave the bug as is, ship with it and don't worry about it.

With most games, especially anything that is multiplayer, you often don't have the option of #2 or #3. Players look for ways to exploit games, so if you leave a bug in that can be taken advantage of, it will be. Thus, the tolerance for bugs in games is actually much lower than in most business/productivity software, because of the abusive potential.

To me, this is one of the major things that makes a large, complex game system like WoW or Everquest really impressive. The lengths to which people will go to abuse any loopholes in a game are pretty amazing, and very well documented. This is a very stark contrast with products like Photoshop or office software, where as long as there is some way of accomplishing what you need to do, the fact that some of the other workflows are maybe broken is not necessarily a mission-critical flaw...it at least has the potential to be ignorable. That just isn't a luxury that game developers have.

Now...compared to things like Air Traffic Control or Airbus flight software, games don't have anywhere those type of life-on-the-line restrictions...that's a whole other class of challenges.

I'm not disagreeing with any of the answers already here, but I find it very interesting that when people think about "the complexity of games" they think about GTA or MMORGs. I think about go and Chess.

Popular games may be computationally intensive with lots of graphics, but that's not HARD per se. Go, on the other hand, is a computationally intractable problem.

Also, if you are taking the technical definition of "complexity", then this is NOT a subjective question.

I don't know how you want to choose to measure 'complexity' or 'impressiveness', but some software you may have on your desktop (like Office or Visual Studio) is probably more 'complex' than any video game, by most measures.

(I think VS these days is like 50 million lines of code, though I am not necessarily a reliable resource here.)

No, games aren't all that special. Of course, like any other large programming project, there are a huge number of conflicting goals, and lots of compromises to make, but in the end, games have the advantage that there are very few requirements. If you're writing a database, then it must fulfill the ACID properties. It must not lose data, no matter when and how you pull the plug on it. If you're writing an OS, something similar applies, it must be rock stable no matter what you do to it. A game also has to live up to a lot of expectations, but very few of them are absolutely essential. It's ok to fake most of the graphical effects. It's ok to fake the world simulation in areas the player isn't observing.

And it's not the end of the world if your game occasionally crashes either. Large AAA games are complex, yes, but they're not the most complex applications in existence. Not by far.

Game development covers a wide range of skillsets and technology, sure, but they also have a lot of leeway, and are allowed to compromise on most of the requirements. It's ok if we can only reach this framerate on that hardware. It's ok if we have to disable soft shadows to improve performance. It's ok that the AI is faked based on "what looks convincing".

Creating a big high budget game is a huge undertaking, no doubt about that. And it's possible that it's the most complex type of application if considered by the breadth of technology, professions and skills involved in creating it. But programming-wise, or in terms of computational complexity or anything like that, nah, it's not all that special.

i really wonder no one mentioned dwarf fortress yet :)

dwarf fortress actually is quite impressive. it may lack shiny graphics, but it does a lot of impressive stuff in open world generation and simulation.

I think there are interesting examples of 'impressive' code in the world of games. The place to look is games for fixed hardware such as games consoles and older home computing platforms. The software to look for is the titles that came out towards the end of those platforms' lives.

For example, Elite on the BBC Micro crammed a 3D space combat game, a market simulation and a map of a whole universe into 32KB. Later the same game was crammed onto a NES. This feat involves hand-optimised assembly language coding in which spending a day to shave off a byte was considered worthwhile.

You can find similarly impressive works on all the 8 and 16 bit platforms. Also look at the sound and graphic demos from the Amiga scene.

The driver for all of this is that you couldn't simply solve the problem with more hardware. Consumers couldn't upgrade the hardware, and were demanding ever more sophisticated games.

In addition, these games are impressive because they were written for devices that weren't initially designed for games. Something as simple as 'smooth 8 way scrolling' was considered a major feature for a game, because the hardware didn't support it directly and programmers had to be really clever to achieve it.

It's possible that those days are over. Maybe someone will push the PS3 or Xbox360 to do something mind boggling, but it seems that you can sell games without pushing this hardware all that hard, so the commercial pressure to do so isn't that high. All you get is small improvements in graphic quality, or larger environments, or more detailed environments.

Increasingly even handheld devices are too powerful to prompt that kind of impressive low level coding. You don't need to twiddle bits to write a 3D game on a modern phone.

So, look for other places where the hardware is limited. The Mars Rover is a good example.

It depends on what you mean by complexity.

From a algorithm point of view, and from a low level optimization point of view, and certainly from a mathematical point of view, then certainly games are more complicated than VS or an operating system.

Though from a code size point of view, from interaction of many different components point of view, and from a need to support (and debug) a multitude of permutations of configurations, then I would say an OS is more complicated.

Off the top of my head, I'd say that the following applications all involved much more complicated code, and much more low-level code than the average game:

• 3D Studio MAX
• The software used to simulate physics and crashes for automotive design
• Meteorological software used to model weather and create forecasts
• High-end OCR software

If you include massive online games, I'd argue yes. They'd have to utilize everything a large scale system would need (distributed system, coordinating those systems, large amounts of data, transactions/reliability to ensure inventories stay correct, etc), all under very tight performance requirements (EVE Online is the major one I'm thinking of).

Perhaps not the most impressive AI, though. I've yet to encounter AI in a game that couldn't be figured out in a couple days.

No.

If we consider all the software as "applications" I would say operating systems are ( for OS are not applications but, well, systems)

One example: at one point Outlook interacted with 10's of million lines of code. No sane game dev would get anywhere near that as it would never run fast enough.

If you include the development process, games are certainly up there.

I would think engines that applications run on top of would be complex. Probably not a lot of lines (like an OS) but very complex as it would need to handle all of the elements and scenarios the designer would need to throw at it AND run optimally.

Since you're talking games, many game developers buy engines and write against that. Some of these engines are written so openly that they're used for several apps that look and feel totally different.

There is a lot of risk management software out there (and other software based on statistical analysis) that is more impressive to me. Its' one thing to create a fake world (impressive in its' own right) but to attempt to predict what the real world is going to do is much more difficult.

I think programs that in some way control the real world is pretty impressive specially if they control some large system.

• The steering computers in the Gripen Fighter which is a aerodynamically unstable plane at subsonic speeds. The computers task is to make it stable and make use of the unstable forces to be able to have greater turn performance.

• A friend of mine works at Jeppesen with a system for scheduling airline crews for major airlines. It must take different work rules for different countries and manage to schedule the crews so they hopefully go on and off their shifts close to home. Pretty impressive I think...

Someone mentioned air traffic control software - I'm fairly sure that it is unbelievably complicated and reliable, but for me it's got to be the global airline ticketing system - amadeus I think it's called.

With hundreds of thousands of flights and destinations and pricing options it's just unbelievable that it can serve requests in real time to basically the entire world.

I have written a bit of software that calculated room prices for a hotel. This wasn't for a big chain or anything, just one hotel - not that big even. and the code that took all the different variables and rules and returned the price was ... enormous and fairly complex.

To scale it up to all the flights operating now and in the future must be in my opinion the most complicated thing in existence.

Are games the most complex / impressive applications?

Complex? No

Impressive? Depends. There are many kinds of impressive.

For example in fault tolerance and correctness, it's probably code for medical or aerospace applications.

In scalability I'd say Google or Amazon.

But the thing that games excel in, is getting most performance out of the hardware that is available. With other applications there is usually a point where you have enough hardware power to not care about it, but in games you can always make better rendering, better AI, etc. So performance will be a high priority for the foreseeable future. In this category games are very impressive.

Short answer: Yes. Although I'm answering this question: "I was thinking today about what could be the most complex / impressive application ever written." rather than which is the most complex / impressive.

Imagine trying to develop a game that modelled the entire universe and allowed you to play it with [x] superpowers. Effectively, you can turn a game into a simulation of ANY complexity, up to as complicated as all known physics and then throwing non-physics into the mix! A video games, by its very nature, can be as simple or as complex as you want to make it.

To my mind that's the beauty of games development. You can create a world to whatever level of detail you want. Anything you can imagine, you could turn into a game. Theoretically.

Most of the modern, graphics-oriented games, as programs, aren't particularly impressive or complex (they may be complex games, but the concepts for programming them aren't).

I find the natural language parsers for some text based games impressive.

Sheer massiveness in either data or lines of code might be impressive, but any given mark set there will shortly be surpassed. Complexity of implementation can be extreme (e.g., the myriad interaction of all the APIs that Microsoft has put into Windows over the years), but there's no underlying need for all that complexity. What are the programs that have underlying, unavoidable complexity?