Will SwiftPaws work on bare ground (no lawn)?Updated a year ago

It might fine - but you'll be the best judge. A good rule of thumb is to think about how you would fair running on the surface you're considering: if you think you would get hurt if you slipped or fell, it's probably not good to run SwiftPaws on it.

Excessive dust, loose gravel, standing water, mud, debris, etc. might not be the most ideal surfaces to play on.

That said, if your back yard is more ground that lawn, you should be able to set up and run a course just fine. All you really need is careful planning, strategic placement of the pulleys to avoid slippiong on loose dirt on turns for example, and a willingness to learn by trial and error.