No revenue estimate for GOG — its rating/review counts don't calibrate to sales the way Steam's do. The Steam version is estimated at $1.9M — a different platform, not this one.

The Solus Project

A single player exploration driven adventure with survival elements, set on a mysterious and seemingly uninhabited alien planet. Survive through exploration, and unlock the mysteries of Gliese-6143-C. From the creators of "Unmechanical" and successor to "The Ball". Adventure - Be a pioneer, an archaeologist, and an astronaut to explore a mysterious alien planet. The adventure has a beginning and an end, but it is a harsh world. A mistake will cost you your life. Explore - Unlock the depths of the uncharted planet, and discover the secrets buried deep below. Delve into huge cave systems and tombs and uncover over 200 secrets. Survive - Survive the extreme climate, tornadoes, storms, meteors, lightning, and not least the dark secrets buried beneath the surface.