I'm gonna wait for Steam version
Free work is ok if it's not-commercical project, such as modding for game. If it's commercical and they're going to make money off your work then it's unfair.
Corona Renderer Tutorial: Saving Render Elements
In this tutorial the developers of Corona Renderer software show the basics of utilizing HDRI maps and using environment overrides.
© CoronaRenderer, 2015 YouTube Link