Been thinking hard about this. The actual mechanics of the host/player roles and interactions are complex but not complicated.
The hard part is coming up with anti-collusion incentives. There's pretty much no way around having something like a pseudonymous reputation market / insurance / collateralized trust, with trusted hosts doing their own KYC
Basically one of the biggest roles of the large poker sites is anti-fraud. When it comes to multiplayer games, there's only so much you can enforce using crypto.
This is why I think for a poker DAC you use the block hash as your random source. You need a modified poker game where knowing the hand of another player with whom you are colluding gives you no advantage over a 3rd party. This means that you have to simulate an infinite deck such that holding an ACE in your hand does not preclude the other players from having the same ACE.
Now the challenge is to
Knowing the hand of another player irregardless of whether there can be the same card out is an advantage, and a very big one when it comes to betting strategy and making every call/raise/fold decision.
I don't like the idea of messing with the rules of the game, there must be some better way to curb collusion without distorting the odds or changing the advantages for the more skillful player.
If you had enough players, randomizing opponents at the start of each hand and hosting tournaments can make there less of a chance of knowing your opponents. Probably many other ideas...