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 $352.6K — a different platform, not this one.

Slipstream

Slipstream is a racing game inspired by the visuals, music, games and cars from the late 80s and early 90s. It's built on a custom game engine, with an authentic retro feel and unique graphics. The soundtrack, drawing from synthpop and jazz fusion influences, sets the tone for a race across a variety of exotic locations from all around the world, including cities, deserts, forests, mountains and beaches. Drifting and slipstreaming mechanics add depth to the driving gameplay, and the result is a challenging and exciting experience. Features Authentic pseudo-3D game engine with 2D graphics, just like the glory days of the arcade racers. 20 Different tracks, set on a variety of exotic locations all around the world... and beyond. Local multiplayer up to 4 players! 6 Game modes: Grand Tour, a road trip through exotic landscapes, with branching paths and rivals to race against. Cannonball, a freely customizable race mode with optional traffic, rivals and other racers Grand Prix, a championship mode with five races back to back and money prizes used to upgrade your car! Single Race, just a race in any of the game's 20 tracks Time Trial, a solo race against time  Battle Royale, an elimination endurance race mode 5 Car models, each with its own specs and playstyle. Original soundtrack with 9 exclusive songs + you can add your own music. A variety of graphical options to customize the game's visuals, including 30fps mode, CRT and NTSC filters.