Kudo Tsunoda of Microsoft Game Studios has said it is unlikely to be possible for developers to patch their existing games to make them compatible with Natal.
While Microsoft is able to engineer other publishers' titles to work with the hardware, Tsunoda told Destructoid, a significant amount of code has to be altered first.
Microsoft has already used several older games to showcase Natal in action - including Burnout Paradise at E3, and, at Tokyo Game Show, the Xbox Live Arcade title Space Invaders Extreme and Namco Bandai's Beautiful Katamari.
However in practice, said Tsunoda, it is more likely a publisher will have to re-release the game in its entirely in order for it to be Natal compatible.
The information comes on the back of Sony's announcement that a number of reworked games will be compatible with the PlayStation 3 motion controller. Some, such as Resident Evil 5: Director's Cut, will be new releases, but others, including LittleBigPlanet, PAIN and Flower, are expected to work following patching.