Currently the idea of having poker directly on-chain is in the early stages and my idea is to have an option for people to create their own tournament.

This is what I have initially thought of:

The ability for the host to determine prizepool for freerolls and participating players should be able ro add to the prizepool if they want to do so.
Tournaments with fixed buy-in should have fixed paid finishes (determined by the host and number of participants) or top x% (also determined by the host).

Both paid tournaments and freerolls will have x% fee to the house from either buy-in or prizepool