Until recently, the cutting edge of games in terms of graphical power, physics, AI and objects rendered was the PC - specifically Microsoft Windows on an x86 or AMD64 platform.
The large increase in computational power of consoles relative to a PC from the 6th to the 7th generation, however, has seen numerous graphically state-of-the-art projects being done exclusively or jointly on consoles. Relative to the console market, the Wintel platform is becoming an equal. The most commonly targeted 'high-performance' platforms today include Xbox 360, PS3, Windows and Mac OS X (the Wii, while seeing very high sales in hardware and software, is not the focus for graphics-intensive game, though it can be considered to be capable of supporting them. The same is true for other PC operating systems.)
Microsoft's Direct3D API has long been the most used graphics API for 3D games. Its competitor, OpenGL, is generally as capable but has not been adopted by game engine creators primarily due to the Direct3D lock-in with WinAPI on the desktop. However, Direct3D/DirectX has three main disadvantages:
1) It is not portable. The PS3 and Mac OS X do not support it at all, while Xbox 360 uses a cut-down version that requires a partial rewrite to support it. The Wii and alternative OSs such as Linux also do not use it, so if they were to become more important platforms for cutting-edge graphics then the limits of Direct3D would be felt even more.
2) The install base is fragmented. DirectX 10 is only available on Windows Vista which has less than a third of the market share of Windows XP and only with new (late 2006 or later) graphics hardware only possessed by 9.66% of gamers (source: Steam survey) , meaning that developers can't solely support the new API without losing over 90% of PCs. At the same time, developers cannot just support DirectX 9 in a new engine, because it will soon be unmaintained and unsupported. Worse, DirectX 10.1 is only supported on ATI HD3xxx series cards on Vista , and this precise setup is only possessed by 0.24% of gamers (source: Steam survey), so the absolute latest version is not even worth making a single game with. Which of the three versions does a provider support? With OpenGL, the majority of users support the latest version, and almost all of the console versions are derivatives of that same version.
3) On a console, hardware constraints mean that much more low-level optimisation is needed to achievethe best performance. OpenGL, being an open specification, is easier to optimise and has greater potential for performance.
Therefore, I predict a shift towards OpenGL development in new game engines, and this will increase the portability and future support of most games using these engines. Much of this applies to other platform-specific code like .NET, WinAPI, Cocoa and Carbon too, so games will depend less and less on particular platforms. This will open new opportunities like an increased number of PC-only franchises appearing on Mac OS X, Linux and all three of the home consoles.
