This is another swing at the low-poly visual style I tried for in my last test. This one's a lot better-looking and includes actual Helios gameplay (though slightly dated). Take a look:
This level was done using Level Streaming for the Nature and Mechanical worlds, meaning we streamed in all of the assets, sounds, volumes, and Kismet required for one world while streaming out those required for the other world.
The level-streaming system is remarkably convenient in terms of world-building, because anything we wanted to exist only in one world, including otherwise difficult things like Post Process Volumes and sound effects, we only needed to put in one world. However, when cooked into an executable there's a jarring lag when streaming levels, so we had to find another solution.