By skyforbes I'll start! Mine is Rag Doll Kung Fu. https://store.steampowered.com/app/1002/Rag_Doll_Kung_Fu/
It's a fighting game where you control the character by dragging their hands and feet making movement weird and slow. I think I played it for 30 minutes and never opened it again 🙂
What is the weirdest / most obscure game in your Steam library?