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 $140.7K — a different platform, not this one.

Avernum 2: Crystal Souls

Avernum 2: Crystal Souls is an epic, indie fantasy role-playing adventure in a unique, massive world, full of strange caves, cunning dungeons, and the alien inhabitants of the underworld. Fight to complete up to three game-winning quests. Explore a massive nation of tunnels and caverns, seeking over 100 towns and dungeons. Master over 60 spells and battle disciplines and hunt for hundreds of magical artifacts. The surface world is commanded by the tyrannical Empire, the eternal power that controls all known lands. Everyone who spoke out, misbehaved, or didn’t fit in was cast into the dark, volcanic pits of Avernum, far below the surface. They were meant to die. Instead, these exiles survived, gained power, and struck back. They assassinated the lord of the Empire. Now the Empire will have revenge. They have invaded Avernum, seizing cave after cave and destroying your people. Your land needs a hero, and it needs it now. If you can’t find a way to stop them, and soon, you are all doomed. Epic fantasy adventure with over 40 hours of gameplay. Explore an enormous underworld, with multiple nations, alien cultures, and over 100 towns and dungeons. Three separate game-winning quests. There are many ways to fight the invaders. Do just one of them or all three! Unique races and settings make Avernum different from any adventure out there. Dozens of side quests and hundreds of magical artifacts. Rich game system with over 60 spells and battle disciplines and a multitude of beneficial character traits to choose from.