I made a prototype for a GM-Free combat system that uses a card deck. The main idea behind it is you don't know what anyone else is holding in their hand, including the monster, so you have moves to see cards and move cards around. Once you figure out what other people have in their hand, you can do moves together for extra effects.
It hasn't been tested though, so I don't know how balanced it is. But I went ahead and published it as "in development" in case anyone who wants to take it for a spin