None. I’m a stickler for the rules so I strictly follow the rules as they were taught to me. Which of course includes such classics as putting any fines in the middle to be collected when you land on Free Parking.

I was always a fan of allowing direct trading of properties between players, houses/hotels included, but I also hardly ever played with groups that got hung up on the resulting problems.

At one point, my sisters, cousins, and I were in favor of any rule that allowed the game to be over quicker, or could screw-over the person in the lead, or allow the rest of the table to cooperate to take the lead player down a notch or help the player closest to bankruptcy.

Okay, okay, we were fickle and naive. We either wanted the game over quickly or to put hotels on every property without anyone going bankrupt. Monopoly is the game to bring out if you want to explain what House Rules are for, or to teach players about collusion and market manipulation/regulation.

How about the Real Life version, where each location starts with 4 houses and is owned by the bank (landlords). You must pay the bank “rent” for the location that you land on it. The last player that hasn’t starved to death wins.

If someone brings Monopoly, the rule is that we have to introduce them to better board games.

My go-to board game for people who don’t want to sit through an hour of set up and another hour of rules explanations is Nightmare, a 1991 Australian VHS “horror” (read: cheesy) board game where you go around the board trying to collect keys enough to win the game. It’s not that fun mechanically, but it’s always a fun time with friends.

Going full capitalism. I.e:

Investment: You sponsor another player for xx number of rounds with yy amount of money, resulting in yy/total value amount if shares in that player. The affected player can offer to buy back their shares early or pay a fixed amount with interest (like a loan) at the end of the xx rounds. If multiple players do this and collectively have a controlling share of a player, they get to choose what that player does every other round. Including selling off property or using kept cards.

Theft: like the official ‘break the rules’ version, you can physically steal from other players/the bank. If by the end of your next round no one has called you out, you announced it and can get away with it. Otherwise straight to jail and triple the value of what you stole goes to whoever caught you.

Slums: in exchange for reducing rent owed to you by another player, you can take one of their next dice rolls and add it to your own in your following round, or just trade movement for rent in general i.e. they can’t move their next round in exchange for not paying you rent.

Privately owned utilities: if you own both the utilities you can take a percentage of all rent paid at any point, instead of the rent on landing on the utility.

Just for fun, three card draw: if you land on chance or community chest you can pay an extra two hundred to the bank to pick two additional cards. But you must play or keep all cards.