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 $2.7K — a different platform, not this one.

Iron Dungeon

For fans of roguelike action games, Iron Dungeon offers an exhilarating combination of twin-stick shooting and 2D platforming, infused with roguelite elements. In this game, you will explore a perilous underground military complex that has reactivated and resumed production of combat clones. As one of these clones, your mission is to uncover a way to the surface and discover if there is still life on Earth. But with dozens of weapons, gadgets, and upgrades to find, and enemies to fight at every turn, the journey won't be easy. Standing still is dangerous! Dodge bullets and aim well to survive! Do not spare your enemies because you will receive precious shards that can be spent on improvements by defeating them. Show precision and skill! Activate platforms and jump boosters that will help you get to the most inaccessible corners of the underground maze to get the most valuable items. You must always find out which maze you will find yourself in next! Dozens of random items await you to help you survive and advance further. However, if you die, you must start from the beginning. And yes, no meta-progression, just your skill, and a little luck!