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 $7M — a different platform, not this one.

Rogue Legacy

Rogue Legacy is a genealogical rogue-"LITE" where anyone can be a hero. Each time you die, your child will succeed you. Every child is unique. One child might be color blind, or they might have Tourette's. They could even be a dwarf. That's OK because no one's perfect, and you don't have to be to win this game. But you do have to be pretty darn good because this game is HARD. Fortunately, every time you die, all of the gold you've collected can be used to upgrade your manor, giving your next child a step up in life and another chance at vanquishing evil. A genealogical roguelite where every death results in stronger children and a fresh new look at tackling the castle minions. More than 30 unique traits affect gameplay in unique ways, such as Colorblindness, Gigantism, and Irritable Bowel Syndrome. Procedurally generated castles that extend replay value by making every attempt a unique experience.