business - Why would a game developer write their own engine instead of using existing ones?

I have observed that many big and well-known game developers often develop their own engines. Examples include Valve, Crytek, Ubisoft, Epic Games and Square-Enix.

Could it simply be because they can, or is it likely that existing engines do not meet enough requirements, so we would develop our own? I can hardly imagine a game that requires a specific engine. The likes of of Unity or Unreal are simply enough to make any kind of game; even if not, they have source code, which can be modified to satisfy even some extraordinary needs.

Why would a game developer write their own engine instead of using existing ones?

Answer

There are several reasons a studio may choose to "build" instead of "buy" their technology:

• Legacy technology; a studio may have started building their own toolchain before there was existing, viable middleware for it.


• Specific requirements; a studio may have a particular collection of requirements that is not well-suited to existing middleware or


• Budget concerns; a studio may not be able to afford the expense or contractual obligations of existing middleware.


• "Not built here syndrome;" the studios technical leadership may be wary (reasonably or unreasonably so) of technology they did not build and therefore do not fully understand.

In general, it does make good sense to own and control the things that are critical to the success of your business, and to outsource those that aren't.

For some studios, the design or storytelling aspect of their games may be the critical resource they expect to capitalize on for success. For those studios, it makes sense to simply buy technology that will allow their designers to realize the appropriate vision.

For others, technology may be the foundation for success. Studios that build MMOs, for example, generally will need to build that infrastructure themselves because it is critical to their success (and existing middleware is generally inappropriate, at least for larger, "AAA" titles).

Note that some of the studios you listed (Crytek and Epic in particular) have basically stopped trying to be dominating forces in the games market directly, and almost certainly make far more as middleware vendors than they do as game developers.