Steam is full of asset-flip garbage and clunky "chase-the-fad" nonsense. But in an environment where only the best of the best get any real attention, what's your secret "I can't believe I ever stumbled across this" gem?

Bonus points if it feels personal or revealing of the creator, but that's not necessary. Bonus points if its fun to play, but again not necessary. My only real requirements is that almost no one has heard of it, and the project was eventually finished. What I'm looking for is the weirdest "complete" experience you've ever found on Steam.