Monopoly

Trading out of debt

If placed into debt, a player must pay a debt as fully as possible on the spot. However, the player can trade to raise money to pay this debt if need be. But this trading can only take place if it raises enough money to pay the debt. If it does not, all trades are cancelled and the debtor's property is handed over (the standard bankruptcy rule). So if you have no cash and land on a £500 rent property, and another player offers to buy a property off you for £800, that deal can be accepted and the money used to pay the debt. If the offer is for £300, the deal cannot be accepted.

The rationale: it makes sense that a player who is rich in property should not be ruined by a momentary poverty in cash. However, trading to get out of debt can be abused by a debtor. If driven to bankruptcy, they could sell all their property for a token price before it is taken off them as a "fuck-you" move. Therefore if any trading is allowed, it must be genuine.

(Not) charging rent and cooperative play

There's nothing in the rules that states that a property must collect a full amount rent when it is incurred. In fact on the spot deals can be made - the property owner can let the rent slide, accept a lesser amount or take property instead. The only limitation on any deal made is that it must be instant - a deal cannot be made that involves any future behaviour or transaction (e.g. "You can pay me next turn"). Put another way, deals can only be held to the moment. You could accept a deal that invokes future behaviour, but there's nothing enforcing such a deal. You have to take it on trust.

This leads to an interesting tactic where two or more players can form a cooperative, where they agree to not charge each other rent. In the mid- to end-game, this makes for a killer combination. The cooperative players are effectively playing against one less opponent and so in a 6 player game will be paying 20% less rent.

It's difficult to legislate against this style of play because an occasional leniency in charging rent and full cooperation are points on the same spectrum. Perhaps it is self-limiting, because other players can always form a cooperative in response. There is also a big temptation for cooperative members to defect when the chance comes for a lucrative rent.

Free parking

A common house rule is putting all taxes and fines into a pot, to be won by anyone who lands on