Trading game online: how to work out a fair price for the city that completes your country

Ahmed Moaz · 31 October 2026

The hardest moment in any trading game online is the offer. You hold two cities of a country, a rival holds the third, and you have to name a price. Ask too little and they refuse because they feel robbed. Offer too much and you have paid for the whole game. In Property Rush, the property trading game I build, I gave my bots a rule that answers this, and it works just as well for a person with a pencil.

How can you put a number on a city?

The rule counts several things, and these four matter most here.

• Cash counts at face value.
• A city counts at its printed price, less the cost of lifting any mortgage.
• A lone city counts at 60% of its price. This is a city you hold with no others in its country, and it earns little and mostly serves as a chip to trade.
• A complete country adds a bonus: its total price plus half the cost of three houses on every city. That is what makes a set worth having.

The bonus is the interesting part. By this rule it is worth:

What is the fair price of Cairo?

You own Giza and Alexandria. A rival owns Cairo alone. Cairo costs 120.

For you, owning Cairo is worth its 120 plus the Egypt bonus of 555: 675. For the rival, Cairo is a lone city, so it counts at 60% of 120: 72. Any price between 72 and 675 leaves both sides better off by this count. The middle of that range is the even split.

Add the two figures and halve them: (675 + 72) / 2 is about 374. That is roughly three times the printed price. By the same rule, a bot that wanted Cairo from you would have to offer at least that much in cash or other value.

Does the same method work elsewhere?

Try two more cases, each with a buyer who holds two of three.

• Venice, price 130, to someone holding Milan and Rome. Value to the buyer: 130 plus the Italy bonus of 880, so 1,010. Value to the seller as a lone city: 78. The even split lands at about 544.
• Osaka, price 240, to someone holding Tokyo and Kyoto. Value to the buyer: 240 plus 1,345, so 1,585. Value to the seller: 144. The even split lands at about 865.

Notice how fast the numbers grow. The dearer the country, the more a single city is worth to whoever completes it. Osaka at 865 is more than half of the default purse of 1,500, which is why such deals often need a swap of cities, and not cash alone.

What should you do with this at the table?

1. Count the cities you need and price the bonus for that country.
2. Work out the seller's floor. If it is their only city there, that is 60% of its price.
3. Work out your ceiling: the city plus the bonus.
4. Open on the seller's side of the middle, to leave room to move, but never below their floor.
5. Fill the gap with cash, a swap or a pardon card, whichever the seller needs.

Boardit lets either side put cash, cities and pardon cards into an offer, so you can build the exact bundle that makes the sum balance. One rule to remember is that a city cannot change hands while any city in its country carries buildings. Sell the houses first.

Is this the price a person would pay?

Not always. A rival may place a higher value on blocking you, or fear your rents less than I assume. The measure also ignores what you will pay in rent if the rival builds elsewhere. Use it as a map of where a deal can exist, not as a tariff.

Even so, it explains something puzzling at many tables: why a rival turns down 150 for a 120 city. They are not being greedy. They know what the city is worth to you.

Property Rush is an independent Monopoly alternative, and its trades are where the rules ask most of your judgement. Practise the arithmetic once at home, then take it to a table and play with friends.

Boardit is not affiliated with or endorsed by Hasbro.

Ahmed Moaz builds Boardit, a free browser game site.