Most of the time if there is gambling going on..it could be poker of some kind, liar's dice...you could try to play most gambling game. You might have to change the name...
Deadlands Roulette is a good one. We get a dragon to stand in the middle with a spell shield on, and everyone else stands in a tight circle around him with no spell shields or dodges. Then you take wagers on who's going to move out of the way, before the dragon tosses an Obliterate packet into the air.
It's like a sports book, except the bookie takes bets on whether the pantherghast wins or loses. Actually, nobody do this, I'm making this my "I want to sit in the tavern and eat" NPC.
Dragon Roulette Isn't a Thing... but "who throw's faster dragon with an oblit, or dragon with a spell shield" at an unspellshielded PC is totally a thing. We call it "Shenanigans"... Spell Shield won, barely.