These games employ the fundamental casino model of making money from intra-player competition that the house stays out of – taking a rake (small percentage) from the winner.
Each has their own style, but the general pattern so far has been to require at least 2-4 players to participate and to generate a random pot size for each round. The players play whatever the game is, and the winner gets the pot minus some sort of rake amount. That’s pretty much it for this branch for the moment.
Early examples include: