Outerra looks cool. Everybody love seamless ground to space transitions, its a real crowd-pleaser.
Unfortunately, Outerra is its own engine. It would be impossible to merge two 3D engines together, so we can't use this with Unreal. We also don't plan for outer space or seamless worlds. This is to keep the focus of design to one planet, and also to reduce the need for complex servers for seamless worlds. In order to survive on an Indie budget, our servers have to be as simple as possible and not consume much CPU or bandwidth.
But ty for the suggestion, it was fun to check their stuff out.