Download from apps.rebble.io
Hex Time is a watchface for the Pebble smart watch that displays the time in hexadecimal. It's written C and uses the Pebble SDK. Orginally developed and published to the Pebble app store in 2015.
I wrote the code after winning a Pebble at a the Bluemix IoT and Drones Hackathon during Devoxx London 2015.
Unfortunately in 2016 Pebble Technology filed for insolvency but the app can still be downloaded thanks to the awesome work by rebble.io.