Apple has today added a new guideline to the App Store Review Guidelines, the first clause specifically targeted at Apple Watch development. This rule that Watch apps that only tell time will be rejected has actually been enforced since Apple started accepting WatchKit submissions as many developers complained to find their apps had been rejected for this reason. The documentation change now formalizes this rule into an official policy.
The Apple Watch does not currently allow third-parties to create custom watch faces. Users are limited to the choice of ten faces that come pre-installed. Most of these faces can be customized with different features and complications (info panels) to suit user’s preferences, but it still leaves many eager for a wider choice of clock faces, especially when you consider that one of the ten faces available is Mickey Mouse.
Hope for third-party faces is resting on Apple’s announcement of a native SDK, which it has promised for later this year. It is very possible though that the native SDK will only allow developers to create apps, not system-level watch faces. As a compromise, there has been some speculation that Apple will add support for third-party complications but not whole watch faces.
Apple does seem to be considering adding more first-party faces soon, though. The Help Guide includes this paragraph:
Apple Watch includes a variety of watch faces, any of which you can customize to suit you. Check frequently for software updates; the set of watch faces that follows might differ from what you see on your Apple Watch.
This seems to imply that forthcoming software updates to the Apple Watch firmware will ship with more watch faces to choose from. At least, that text suggests that Apple has plans for changing the set of faces it bundles with Watch OS in the near term. In September, Apple showed two watch faces, Photo and Timelapse (Timelase is the third screenshot above), in marketing materials that disappeared by the time the Apple Watch was released. It is not unconceivable for these faces to make a return in future.