there are around 3,000 iPhone apps that have been built exclusively for the Apple Watch. Search on the Apple Watch version of the App Store looks alot like a the version accessed from an iPhone:
No Trending or Game Sub-categories yet.
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No one can say for sure where wearables is headed - and how big the opportunity is. If nothing else, the Apple Watch release challenges mobile app publishers to simplify their UI, create experiences using inputs from the wide range of data inputs available and unique to mobile (phones and wearables) , and be there when a users is likely to need them.