No revenue estimate for GOG — its rating/review counts don't calibrate to sales the way Steam's do. Reviews and prices only.

Contraption Maker

Play over 200 official puzzles and over 1,000 user created puzzles in the Workshop. Use the many characters that interact in amusing ways. Play online to build contraptions together with up to 8 players in the Maker Lab. Make your own games with the built-in JavaScript Editor using Contraption Maker's physics and parts. Build your own ingenious contraptions and puzzles and share them. Create your own Cheese Factory or anything else that you can imagine. You can make large elaborate endless machines.