The problem is, that without a clear cut, there should be hundreds of systems tracked. If you notice, the site isn't even tracking PC sales either. And PC has a lot bigger impact on games market than the Apple products.
Then, the DLC games are virtually impossible to track because of the lack for a source of information.
Ei Kiinasti.
Eikä Japanisti.
Vaan pannaan jalalla koreasti.
Nintendo games sell only on Nintendo system.