Light flow is pretty amazing and I'm surprised phone makers haven't at least integrated some of the features.
It started out as a way to do custom LED sequences, but you can also set custom vibration patterns (at the millisecond level) for every type of notification.
The power of vibration is heavily under-appreciated (less by Apple than by everyone else).
Our phones are great at precisely creating many different vibration patterns and humans are pretty good at distinguishing them. We're even more sensitive when it's happening on our wrists.
Yet instead of using this to create personal and expressive notification experiences, most manufacturers opt to barely give the user a choice and just turn on the vibration motor for way too long (or do that twice!), simply creating a sensation of pain every time.
It started out as a way to do custom LED sequences, but you can also set custom vibration patterns (at the millisecond level) for every type of notification.