Disclaimer: I am not a video game developer. But I do have a “hobbyist” interest in it.

Most of the AAA games you see are made using Engines. They aren’t written from the ground up. Think of an engine like a framework. You have .NET framework, Java SDK, Cocoa toolkit.

All things to make your job of creating software easier and abstracting away the kitchen-sink code. It’s necessary, but writing it every time is very unproductive.

Using these engines developer can build their game and not have to worry about some of the underlying code. (Make no mistake, game development is one of the hardest branches of software engineering.)

For example, Unreal Engine 4 has a killer development kit and studio:

There are many different engines out there. Some paid, some free, some more down to the metal, others offer a higher abstraction.

For example:

• OGRE
• Unreal Engine
• Unity
• Source
• and many more…

In reference to gbjbaanb’s comment, some of the things that make game programming fun is the limited lifespan of the code base and the lack of requiring precisions. For example, if you’re designing an FPS game, and your movement algorithm sometimes places your game character a few pixels off, it’s no big deal and chances are no one will notice. If you’re designing a piece of business software and occasionally your sum function places you a few dollars off, that’s a much more serious bug. So when designing games some aspects can be much less precise (and only have to pass human testing, rather than an automated test suite which checks that the answers are precisely correct).

My experience has been that game programming, especially for real-time games, is a much different experience from…almost any other software development I’ve done, maybe except for GUI work. It’s something you have to try!

The answer is “engines”. A lot fo games are built ontop of various graphics and gameplay engines that are basically, big libraries or frameworks.

In the OSS world, take a look at Ogre for an example, for commercial games you have stuff like Source.

There are other factors at play, like a lot of the code is disposable and wouldn’t pass muster in a business environment – but that’s because the limited lifespan of a game, and the accelerated development timescales, mean the code is (almost) designed just to work, not to be maintained.

Unity3D is really nice. Here’s some points I like about it:

• it lets you build games in a platform agnostic fashion, and then automatically creates deployables for either Windows, Mac OS X, Android, IOS. This is true for the current version (3.x). Apparentlly version 4 will let you deploy on Linux as well:

http://en.wikipedia.org/wiki/Unity_(game_engine)#Major_features

• Even though you need a payed license to actually use it (commercially), you can donwload a free version in which you can use most of the features (i.e. you cannot for example make deployables for the mobile platforms). It gives a great way to preview the thing before you decide to buy it or not:

http://unity3d.com/unity/licenses

• Works with most 3d modelling software (I prefer 3d Studio Max, but it supports others as well):

http://unity3d.com/unity/editor/importing (scroll down a bit)

• Coding (scripting) can be done in C# which is a nice language, with a good API and compile time checks. Comes with a good dev environment (IDE and everything). If you want something different, it supports Javascript as well.

• Has very good physics support (collisions, gravity, forces, etc):

http://docs.unity3d.com/Documentation/Manual/Physics.html

• Has an asset store that lets you buy various models, scripts, animations etc, and depending on your skill (and wallet) you can get/modify those to quickly obtain decent resources for your game.

• Last but not least, it’s decently fast. Check out the mobile demos, IMHO they move quite well and have very decent graphics:

http://unity3d.com/gallery/made-with-unity/game-list

Here’s one nice Unity project I’m currently waiting for:

Brian Fargo’s Wasteland 2

They have a nice blog entry about why they chose Unity, as well as other discussing how working with it goes along.

ID Software is one of the vendors which usually publishes state of the art games. A few years later they often release those as open source. On http://fabiensanglard.net/quake3/index.php you can find an analysis of the Quake3 source code. This is a quite verbose description and even though Quake3 is quite old meanwhile the concepts there should still be relevant for modern games.

And yes, if you want to build a state-of-the-art modern fast, competitive game engine you will have to know all those low-level pieces. If you don’t want to care about those: There are different engines (quake3 engine or the ones from other answers) available but well, then you’re not creating a new revolutionary game 😉

As many answers mention, game engines and libraries play a big part. However, do note that this applies to mid-big commercial games more than to small “indie” games.

For example on mobile platforms most games are written using only a set of relatively primitive libraries rather than relying on full-blown game-engines an frameworks. They do exist, but for the most part it’s about re-using your own code from earlier projects.