Since the vast majority of gamers today still use Windows XP operating system (OS) and cannot take advantage of DirectX 10 application programming interface, Valve Software believes that it hardly makes sense to jump on the DirectX 10 bandwagon just now, as certain DX10 hardware capabilities can be used even in DirectX 9 environment.

According to statistics from Valve’s Steam software distribution system, there are about 8% of gamers who use Microsoft Windows Vista operating system and 90% of those who utilize Windows XP OS. Meanwhile, over 11% of computers with Steam installed are equipped with a DirectX 10-compatible graphics processing unit, though, this does not guarantee that they use Windows Vista: only about 2.31% of users have a combination of a DirectX 10 GPU and Windows Vista.

“There are far more customers with DX10 hardware running on Windows XP than Windows Vista. If you’re going to try to take advantage of that hardware, your customers are telling you, make sure it works on DX9 API,” said Gabe Newell, the founder and managing director of Valve Software, in an interview with Game Informer web-site.

This is not the first time when a major game developer indicates lukewarm attitude towards DirectX 10. Earlier this year John Carmack of id Software said he would not "jump" on the DirectX 10 hardware immediately. Other game developers are also not leapfrogging to DirectX 10 mainly because two most advanced game consoles available today – Microsoft Xbox 360 and Sony PlayStation 3 – are equipped with graphics chips which feature-set resembles that of DirectX 9 shader model 3.0, therefore, it is easier to develop new titles with similar graphics features in mind.

“Right now with the flexibility of DX9, we can take advantage of DX10 hardware functionality through DX9. For example, the tesselator in ATI’s [Radeon HD 2000] hardware is super valuable and we can get to it through DX9, so that’s probably a better investment than going after a DX10 API,” Mr. Newell added.

Another strong reason for not utilizing DirectX 10 for titles that are coming in the next 12 months is because of generally poor performance of contemporary first-generation DirectX 10 graphics processors even in modern games that use some DirectX 10 features.