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 $8.2K — a different platform, not this one.

Whacking Hell!

"Whacking Hell!" is a frantic 2D top-down shooter with roguelite elements. The gates of hell have opened: whack all the monsters before they whack you! Collect their souls, ramp up your weapons and your spells, and become a slaughtering machine! Defeat waves of enemy attacks and nasty bosses by choosing the right path of upgrades. Key features: 5 characters and 5 main weapons to unlock. 3 chapters - each chapter contains dozens of waves of enemies and two bosses to defeat. Acquire special powers and ramp up your skills during the game session, so you can face the ever-increasing difficulty within the chapter. Acquire permanent upgrades in between game sessions, so you can progress in the game. Reveal dozens of monster species in the bestiary. Supports keyboard and game controller.