A secret poker game you can play on the subway

The most obvious issues with this is that the game boils down to predicting passenger patterns, but you're still just comparing two RNGs, which is one of the worst kinds of games. I also don't think this can be called Poker, really. Poker is an imperfect information game, where your hand tells you some information about your opponents' hands.

It would be interesting to read HN's ideas on how you can simulate the shared information part of the game in such a scenario.

In the style of Texas Hold'em, both players could secretly choose two seats each and write them down. Then, you'd collectively choose 5 seats to be the shared "cards."

This next suggestion would stretch the "poker" definition somewhat, but I think it retains the same characteristics (imperfect information, shared "cards").

You start from a shared list of attributes (coat color, presence of a hat, etc.) and designate a row of seats. Each person gets one attribute secretly. You wager after each stop following poker conventions.

Only downside to this is that unlike poker, your hand can get worse after a stop.

This misses the information your secret hand gives you about the other player's chances. In poker if I got an Ace in my hand the chance of the opponent having an ace lowers.

If I got somebody wearing a black coat, this has no impact on the chance of my opponent having a black coated passenger.