It's not all productivity and fitness. WatchOS 3 is going to improve the gaming application of your wrist.
For a start, Game Center support is coming. That's a game changer in itself, as you should be able to track your progress in games, earn achievements, and save data via iCloud.
There's also support for new touch gestures inbound. That in itself could open up new gaming possibilities.
But let's not speculate. Let's wait for the finished product when WatchOS 3 launches later this year.