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 $3.4K — a different platform, not this one.

Der Geisterturm / The Ghost Tower

By 2074 the Earth turned into a scorched wasteland, forcing the population to leave the planet or move underground while two megacorps are stuck in an endless war over the territory and resources. After graduating from the military academy you've decided to join Eberbach Corp as a Robotic Combat Suit pilot... ...but something went wrong. You wake inside a large Robotic Combat Suit with no recollection of your past, and a mysterious man commands you to climb to the top floor. Will you reach it alive or die trying? KEY FEATURES Fight your way through 15 floors filled with dangerous encounters, traps, and puzzles; Tactical turn-based combat against multiple enemies with different strengths and weaknesses; Extreme resource management: the ammo and items are finite, and you have to adapt in order to survive; Original progression system: search for upgrades to improve your armor, abilities, and weapons while the pilot gets better through killing or avoiding enemies; Unique wireframe-like graphics style supported by the atmospheric electronic soundtrack.