Microsoft has posted a list of 212 Xbox games that are backward-compatible with the Xbox 360 - but only next-generation consoles with a hard drive.
The list, which you can view here, contains all the best-known Xbox titles. Games not present on the list will not run on the 360.
Unlike other console makers, Microsoft has chosen to implement backward compatibility in software. The downloadable app converts Intel x86 processor instructions from the original Xbox into their PowerPC equivalents, in the process compensating for the different ways the two CPU types store numbers larger than 255.
Microsoft said the emulation software would be made available to Xbox Live subscribers, from the Xbox.com website - as a downloadable disk image to burn to CD - or direct from Microsoft on CD. Presumably it's then installed on the 360's hard drive, though the website doesn't make this clear.
That leaves anyone who buys the cheaper Xbox 360 Core System out in the cold - it doesn't ship with the 20GB HDD that's part of the standard package.
Todd Holmdahl, Corporate VP of the Microsoft's Xbox Product Group, said that the emulator will be updated regularly as more Xbox titles are "certified" as 360-compatible. That suggests Microsoft is tweaking the code on a game-by-game basis to cope with coding subtleties in individual games that would otherwise break the general-purpose emulator.
It remains to be seen how all this impacts the 360's sales. Certainly, it's traditionally held within the games industry that the success of Sony's PlayStation 2 was in part due to its ability to play old PlayStation titles. That said, backward-compatibility is a relatively new feature for consoles - for a long time, buying a next-generation machine meant leaving your software library behind. Buyers coped with it then - maybe they will now.
The first Xbox 360 customers will primarily be early adopters - probably hard-core Xbox fans, who are going to go for the HDD-equipped version and will understand the issue in any case - and give Microsoft the benefit of the doubt. However, we wonder how many more casual gamers who already own an Xbox will stump up for the new model only to find it doesn't play their games collection. ®