I have this idea for an iwatch game, but I don't think its possible with construct 2...
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As described here:
apple-watch-and-the-cross-platform-crisis
Communicating between Cordova applications and the Apple Watch is possible today thanks to a plugin from Lee Crossley that provides a message passing interface. The primary limitation at the moment for hybrid (read Cordova) developers, is that a watch interface cannot be built with Cordova since the watch does not support a WebView.
(This information is almost a year old, so maybe some improvement has happened)