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 $5.2K — a different platform, not this one.

Spelp

Spelp is an arena-survival game with roguelite elements. With simple twin-stick shooter controls, eliminate thousands of aliens to get stronger. Select from a variety of upgradable weapons and passives to make a unique build and try to survive until the planet is safe. 2 maps available: Stardust is a giant exoplanet where other members of the SPELP program has been made prisoners, save them to form a team. Select members with unique characteristics to perfect your build. A team full of aliens with life-steal and bullet bounces or a team with humans and robots where gigantic black holes do the job for you! The Lab is a more confined space, monsters spawn in wave and you will get no help from the SPELP program to survive against the result of alien experimentations. Diverse cast of characters with unique weapons and gameplay. Variety of weapons and upgrades to make a lot of different builds. Cool boss fights. 20 minutes runs. 5 difficulties. 2 maps/game modes. Keyboard/mouse and controllers (mostly) supported. Unlockable characters Action-packed gameplay