I haven't played around with my smartphone's camera in a while.
It uses a gyroscope that ensures a steady horizon when capturing. As long as I can guide the camera along the horizon, it will capture. Of course, I don't have to follow the earth's horizon. Just starting from the predetermined position of the phone works as well. Therefore, I can dictate where the horizon should flow.
Curving the horizon immediately invokes a camera lens impression. Something akin to a fish-eye lens. It's not perfect. Often I curved my wrist too quickly, creating a small cusp instead of gradual curve. Other times, I was able to rotate the camera near ninety degrees. This instead gave the impression of a landscape waterfall. As if the ground was flowing like water.
Of course, there were many failures trying to make the panorama smoothly capture. Usually the soft gradient of the sky would be cut up in some rotations. I tried repairing one of these photos with photo manipulation software, but it was too difficult and not worth the time.
I've only shown what I've done recently. I'll be playing around with this technique more. It's pretty simple and easy to replicate, so try it out.