What Is A Game Engine?

“What is a Game Engine?”

A “game engine” is a modular piece of design software that allows game developers to create games and incorporates several elements of the design process. I will try and cover a few different game engines, involving ones capable of 2D Graphics, 3D Graphics, mobile and mods and user content.


Unity is a multi-platform game engine that supports both 3D and 2D graphics and has become so popular since its release in 2005 that it has even become the default software development kit (SDK) for the Wii U console. While it was created on Windows and Mac OS X it is now available on a huge variety of platforms (which will be listed below). With a freely available SDK based on Unity 4.6.2 it supports mods and user created content, allowing anyone with an internet connection can download and run Unity, allowing them to make their own content in the game.

Unity was designed for portability and compatibility with a wide range of systems and the graphics engine supports the following Application Program Interfaces (APIs): Direct3D on Windows and Xbox; OpenGL (Open Graphics Library) on Mac OS X, Windows and Linux; OpenGL ES (Open Graphics Library for Embedded Systems) on Android and iOS and proprietary APIs on consoles (Wii U uses a proprietary API based on OpenGL, as does PlayStation 4 while the Xbox One is due to adopt Direct X 12 when it is released.

Unity also supports collision detection, Artificial Intelligence (AI), sound and physics without the use of any third party software.


^ A screenshot from Hearthstone: Heroes of Warcraft.


^ A screenshot from Wasteland 2.

Platforms Unity is available on: Windows, Mac OS X, Linux, Xbox 360, Xbox One, Wii, Wii U, PlayStation 3, PlayStation 4, PlayStation Vita, Windows Phone, iOS, Android, BlackBerry 10, Google Native Client, Adobe Flash, Unity Web Player and the Windows Store.


Unreal Engine is a multi-platform game engine that is capable of both 2D and 3D graphics and was considered one of the best and most popular third-party engines of the last decade or so, although the rising popularity of Unity has splintered that somewhat. It was first released in 1998 and used in the FPS game “Unreal” and has gone on to be used in titles such as Gears of War, the Batman Arkham- series, Enslaved Odyssey to the West, Borderlands and Mirror’s Edge.


^ A screenshot from Unreal.


^ A screenshot from Mirror’s Edge, made on Unreal Engine 3.

Unreal Development Kit (UDK) was released to the public for free in 2009 and while, like Unity, it has now moved towards a subscription based business model, Unreal Engine 3 generation-SDK is still freely available. Even with Unreal Engine 1, the engine incorporated rendering, collision detection, AI and more into the engine without any third party software and made use of the Glide API although it was later updated for OpenGL and Direct3D.

The engine was made with C++ although a custom script called UnrealScript was used for large portions of the Unreal game. Due to its modular engine and a scripting language that made it very easy to mod, the engine became very popular.


^ A screenshot showing how the Malcom character from Unreal Tournament was updated throughout UE1, 2 and 3’s rendering engines.

Platforms Unreal Engine 4 is supported on: Windows, Linux, Mas OS X, Xbox One, PlayStation 4, HTML5 and iOS.


Source Engine is a multi-platform 3D game engine released by Valve Corporation in 2004, with the first game being Counter-Strike: Source and was followed up with Half-Life 2. While developed primarily as an FPS engine to power Valve’s Team Fortress, Counter-Strike and Half Life games, it has been modified and used to create games in genres such as role-playing, puzzle and MOBA.


^ A screenshot from Half-Life 2


^ A screenshot from Portal 2

Source Engine was made with future-proofing in mind so that it could be updated incrementally in line with technological advances while its competitors were updated and introduces compatibility-breaking upgrades. However yet again Source Engine handles AI, Physics, Rendering and Sound etc without the use of any third party software and features have been added throughout it’s development such as HDR rendering and Multiprocessor support.

The engine was written in C++ and the use of content authoring tools such as the Hammer Editor have made it popular due to its moddable nature, with titles such as Portal and Left 4 Dead being the result of fan-made mods based on existing Source Games, or simply experiments in the Source Engine using the Hammer Editor.

Platforms Source Engine is supported on: Windows, Mac OS X, Linux, PlayStation 3, Xbox, Xbox 360 and Android.

Up to this point I have touched on three game engines and mentioned their editing tools etc however now I will talk about an example game made in each engine and how the use of the particular engine affected the cost, team size, time it took to make the game and advantages of using a particular engine.


Cost of development: $3,000,000 (Kickstarter) + $3,000,000 (Steam Early Access and developer’s own money).

Development Team: inExile (under 30 developers)

Development Time: 1 Year + (Oct 2012 to Oct 2013, then almost a year of Beta release)

You can see that Wasteland 2 was a game that cost a lot of money to make and the fact that it was all Kickstarter-funded or word of mouth shows that there was a lot of anticipation for the game. The development team was comparatively quite small at under 30 developers although the head of inExile, Brian Fargo, stated his preference for smaller dev-teams and crowd-funding as it not only let him pick who he worked with etc and kept the team from getting bloated, but it also meant that they had more creative control and did not have to answer to publishers. Deep Silver published the physical copies of Wasteland 2 but otherwise it was entirely developed and published by InExile.

A development time of a year is also quite short but when you consider that the game is text-based over voice-based (although there is still bits of voice acting, just not every line of dialogue) it is not surprising, and content was added after the game entered it’s “beta” phase and the game has received post-launch support since it’s release in September 2014.


Cost of development: $10,000,000 (not including development of the Unreal Engine or outsourced work to Epic Games China).

Development Team: Epic Games (Unsure of dev team numbers)

Development Time: Approximately 3 years (Gears of War 2 was released November 7th 2008 and GoW3 was released September 20th 2011)

Gears of War 3 was a game that cost an awful lot of money to make although compared to some big-budget, AAA games, it was still comparatively cheap. Although I could not find exact numbers on the size of the development team it was most likely quite a large team as Gears of War had become a popular and genre-defining franchise and included outsourcing efforts to Epic Games China to help get the game released on time.

The development time of 3 years sounds appropriate for the size and scale of the game and the use of working on an engine that Epic not only made but had been working on and iterating upon for several years can only have helped matters.


Cost of development: $25,000,000

Development Team: Valve (250 work at Valve, roughly 60 worked on L4D2)

Development Time: 1 Year

In contrast to Gears of War 3, which was a highly anticipated title in a popular series, Left 4 Dead 2’s budget was enormours. While it’s unlikely that Gears of War 3’s budget encompassed every dollar that went into the production of the game, Left 4 Dead 2 had at least a $25,000,000 budget which includes marketing. While the quick turnaround between the original game and the sequel caused controversy, with some fans suggesting Valve were phoning it in, to my mind the range of new content available speaks volumes to the strength of the Source Engine and aforementioned Hammer Tools to make a lot of content in a short space of time.

Certain aspects like character models for zombies, items and textures are obviously re-used but the game only revisits one location from the original game and that is for story purposes. This is also probably a strength of the Source Engine being an iterated design since its release in 2004, rather than wholesale version upgrades like Unreal Engine. Due to this Valve were obviously able to work on an engine that everyone at the company had been using for almost a decade (if you take into account they had been developing the Source Engine alongside Half-Life 2 in the early 2000s).

However it’s worth noting that Valve have confirmed Source Engine 2 is in the works and they are “waiting for a game to ship with it” and I am sure that the lessons learnt in content creation an a seemingly efficient production pipeline will guide how the new engine works and its development tools, the successor to the Hammer Tools.


One thought on “What Is A Game Engine?

  1. Pingback: Game Engines | BossDarkseid

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