Well electric and magnetic forces can be described as distortions of space-time too. Really.

It's just that the equations are *different* for gravity. Don't recall details, it was a long time ago, and involved stuff like tensor calculus.

The late Dr. Robert Forward described a bunch of ways we *could* play with gravity that aren't that far outside the box.

Mostly a matter of engineering problems. Mostly needing to create hyperdense matter and stabilize it. Likely doable, but a major pain.

Check out his book Indistinguishable from Magic