monochrom’s Multi-Player Thumb-Wrestling.

From the website:

It is possible to put together three hands of three players who want to indulge in thumb-wrestling. A nodal network is formed. In a game of three, the player holding tight the thumb which is furthest down is the winner. All other thumbs (further up) have a walk-over for the two thumbs furthest down are frozen already.

Since humans have two hands the left hand can be used to connect even more players to the network. Thus, various possibilities pop up.

Link (via DeepFun)