What's the probability of an endless Monopoly game? (simulating 1.000.000 games in Python) - zigjogos.com

What’s the probability of an endless Monopoly game? (simulating 1.000.000 games in Python)

Games Computers Play
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Monopoly is known to have a nasty tendency of getting endless. I have built a Python simulator that will uncover whether it is really so – and what factors are at play here. 5 different experiments, 1000000 games simulated, multiple graphs plotted, ppt slides created.

(Spoiler: it is actually rather low, if you play the game the right way).

Souce code:
As always, sorry it’s messy.

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35 Comments

  1. The problem is probably house rules, which tend to keep more money in the game

  2. I have the old monopoly app, where I had a stalemate because I set the house rules as such that the game introduced too much money into the economy. Both me and the AI had all the monopolies evenly between us, but I we both had about 24 THOUSAND dollars so the only way either of us was going to loose was for one of us to land on the other's high rent property about 16 times in a row while the other avoids paying rent.

  3. The reason why games normally last so long is because people play "communism rules" where they do anything and everything to keep themselves in the game and share the wealth. The reality of the game is that it should be played in the first 3 rotations around the board, if all but the last two are not practically dead by then you are playing it wrong.

  4. Giving the properties back to the bank makes games last much longer. You no longer gain a major advantage by bankrupting someone.

  5. It looks like you always unmortgage the cheapest. Shouldn't you unmortgage the "best"…. I know that's hard to quantify… but… For a losing player though it'd be his monopoly generally right? Code doesn't seem to do that? Maybe cost to unmortgage vs rent returned. That would make the Rail Roads 25/110 = .23 a better choice then a single of New York Ave. 16/110= .15, Which seems right. it IS a lot more code though…. It might be nice to have some code that did something like "If I have more monopolies then everyone ese, I don't want any more monopolies" Since I don't think the code does that? Also your code is a lot more beautiful then any I've written…….

  6. What game ended in 12 turns??

  7. That soviet monopoly looks way cooler than the original.

  8. I remember the last time I played monopoly with my family, I eventually managed to get a monopoly and had my sister land on it. She had been playing monopoly on her phone a lot in the weeks prior, and got really mad when she found out she didn't have enough capital to pay me, and both I and my parents refused to buy her properties at an overpriced rate in order to prevent her from losing (none of us needed her properties). She insisted I should "let her go" since apparently It is more profitable to not let someone lose, that way they can collect money and pay you even more later. She eventually started screaming, and flipped out and forced us to stop playing since she didn't get to play.
    3/10 would not play again. Monopoly is long, boring, frustrating, luck based and absolutely not satisfying even if you win.

  9. monopoly was meant to be unfun since it was a critic to capitalism

  10. My friends and I do an annual Monopoly marathon, with over 500 custom Community and Chance cards, in addition to game show elements added in. I'd love to see that simulated.

  11. this is why in parties we end monopoly games after an hour, then see whoever had the best position (Most money, properties, monopolies, etc.) and declare that the winner.
    Ex.
    An 8 Player monopoly game.
    90% chance (exaggerated) it’d probably reach 1 hour of playtime. Assuming a move takes 30 seconds.
    Here’s the scenario:
    P1 goes bankrupt (Move 91)
    P2 survives, but they have only 1 property and $17.
    P3 goes bankrupt (Move 68)
    P4 survives with 10 properties, a railroad and orange monopoly, 13 houses, and $1198.
    P5 gets the KO on P1 (KO = forcing someone into bankruptcy by making them land on your property), plus 4 properties and $907.
    P6 gets a monopoly on dark blue, with 5 properties, 2 houses, and $329.
    P7 gets the KO on P3, along with $1398. However, they only have 2 properties.
    P8 has 3 properties, $719, but is in jail.
    We would rank it like this:
    8th: P3 (Bankrupt on Move 68)
    7th: P1 (Bankrupt On Move 91)
    6th: P2 (about to die)
    5th: P8 (P7 and P8 are close, but P7 got a KO and my friends treat Jail as bad (I think it’s a good thing in high pressure situations where the board fills up))
    4th: P7 (Less Properties are crippling, but a terrible situation with P2 and P8 allowed it to salvage the top half, or the disappointment spot)
    3rd: P5 (P6 and P4 have monopolies)
    2nd: P6 (P4 was the clear winner, but this is the mostly likely comeback player, 5 properties (which is great for 8 player monopoly standards) plus players having the possibility to land on dark blue if lucky could allow it to win if things go their way, even with the lack of cash)
    Winner: P4 (10 Properties and a sizible chunk of cash increases your trading leverage, but it gives you a huge advantage because you can pay off a lot, and the other players would have to pay you back often since you have tons of properties)

  12. Чтоп сто… Не думал, то ты из России. Классные видео 🙂

  13. Monopoly is such a bad game

  14. fun fact: monopoly is bad cause its designed to be bad, it was made by socialists to mock capitalism
    im sure someones said it already though

  15. What is the source of the Wow ‼ sound bite at 2:30?

  16. Programmer: I wrote a program.
    Python programmer: I wrote a program in Python.

  17. I'm annoyed you didn't do THE most common house rule: Free Parking.
    All money that would go to the bank from fines and taxes etc. goes to the middle of the board, and the first player to land on the space wins the pot.
    This is MASSIVELY different from just increasing salary, which distributes the new wealth evenly.
    It effectively adds a lottery to the game which can often be game-deciding. I was really eager to see the stats for it…

  18. I played games w/o trading before and they still ended. And I've played monopoly at least 20 times this way.

  19. It also depend on how you trade, i've never really put lot of though about it until recently then i watched some youtuber that played monopoly with unusual (that's how i though of it at the time) trades but after some time theirs trades makes some sense…

    What i am talking about? Well take the value of properties, if you trade a property of 150M for another of 140M with 10M of change, it's a fair trade right? Well… What if it's the last to make a monopoly? for one and not for the other player? is it fair? not exactly, then trade the same 150M value for 2 properties of 120M each and 60M change, so a 2:1 rate but each get a monopoly… it's more equal that way… So the trade simulation could be… pretty hard to do in a scientific manner… say i've got one of the most expensive property that you have 2 of and you get 2 low value one that i have the 2 other, would you accept a trade to get your monopoly for giving me 2 of lower value or will you let it stalemate while another player who do have a monopoly can start to rake up the benefits and build more and more over time taking both of our money?
    What if you are in the opposite situation, you do have 1 monopoly (even if it's the lowest value one) but are offered 2500M for a property that will make them have a monopoly but if you don't they will never have a monopoly and in the end you are sure to win the game (but lose friendship)…

    then i was little and played monopoly i nerver though about this kinds of situation (we even created new currency of higher value for longer game that we paused but probably never finished then we moved the board and lost whose turn it was next or current position of player…) but as an adult i do understand most of the flaws of this game…

  20. must be like %99
    ive only had 1 game end, that lasted about 10 mins, oddly all the other games last hours and we just decide to end it

  21. Someone figured what the worst way to play monopoly is

    1) when a player bankrupts, their money and properties go to the bank, and they start over with the starting money
    2) the game doesn't end until 1 player owns everything

  22. In the no auctions simulation, what happens if the player doesn't have enough money to buy the property at face value?

  23. Instead of the changes to starting $$, I have seen a good variant where you double the price of all properties. This tends to force more properties to goto auction and creates a better strategic experience. I would be curious to see if a similar effect could be made by just making starting capital 1/2 ($750)

  24. You really don't need to be a Mensa-member to understand that with 2 players, who doesn't trade and "block each other out" on properties, it will be a endless game. Because the money you get everytime you pass go, will earn you enough to pay for landing on the others properties

    If monopoly was played according to the rules, it would never take that amount of time, it is with all the "house-rules". To make it clear: If you play monopoly and got "house-rules" like land on free park, you get paid taxes, which is placed in the middle of the board, and get double the money if land on go, you are not gonna win, you are holding up the game

    The way to win in monopoly with 4 or more players, from the beginning buy every property you can get your hands on. If you somehow early on hit the first and 3 in same color, you should focus everything on getting the last one.

    And be aware on hitting 7. Because according to stats, you are gonna do it. And remember with 7 it's no chance of double and new throw. 7 can be, 6-1-1-6,5-2,2-5,4-3 and 3-4.

  25. Interesting how the graphs at the end look like they'd make for good stock market simulations.

  26. There is a relatively common (and bad) house rule of creating a stack from money that is paid to community chess and giving it to the player that leaves jail or something like that

  27. 11:07 if this was real, i can’t imagine what the banker would be thinking, printing 1000s of monopoly dollars

  28. Ok I'm a year late, but what's the quickest a monopoly game could end? And what are it's chances?

  29. Hmm, if trading causes 2 player games to always finish, that means one of the players is making a mistake when accepting trades. Curious how to trade optimally.

  30. someone show this to dan from game grumps

  31. All of the 'infinitely long games' really boil down to a single issue; players make more money from going around the board than they lose to outside sources. As long as this stays true, games will indeed last forever, because the one victory/loss condition in the game can never be reached. This is why not trading pretty much single-handedly kills games; there's no way you lose more money from single rents than you gain back from the salary. I'm willing to bet that the 12% in duels with no trade is the rough chance that neither party will get a single full street, and the slightly diminishing amount of draws over time are due to 'terrible luck' streaks.

    Logically speaking, increasing the starting fund only gives you a single sum of extra money. What this means is that games might last a few turns longer, but if the net amount of money gained per lap is still negative, they /will/ end eventually, regardless of the starting amount. However, increasing the salary (or anything that increases income, for that matter) actively increases the amount of money you get per loop, which in turn increases the chance that the income for all remaining players outranks their expenses.

  32. tfw the USSR bans anticapitalist messaging bc it contains capitalism

  33. why would 2-player monopoly involve any trading? I mean, a trade can only benefit one player or the other, not both.

  34. I loved this video and everything you put together to make this happen. I have two answers that hasn't been address (or maybe I didn't fully understand your analysis) in the cases you presented and I'd love to hear:
    1- Endless games are not literally endless, right? You have a cap of 1000 turns set, and if players go through 1000 turns without having only 1 winner that accounts for an "endless game" if I understood correctly. So my question is, if you remove the cap of a 1000 turns and make it literally endless, would this show that all games have an ending? Maybe the longest game would last 50 thousand rounds, but my belief (and I would love to see the simulation data) is that all games eventually have 1 winner.
    2 – I know this is not part of the rules of monopoly, but another test that came to my mind while watching is the starting capital. Every player gets the same, that's the rule. But what would happen if that is not equal? My guess is that the player with more starting capital would win 99,9% of the times.

    That's all! Again thanks for all you've done here, you have a new suscriber!

  35. monopoly should never take much more than an hour to finish, 1.5 hours tops. If the game is going on and on you are doing something wrong. Most players should have little to no cash left after just a few times around the board. A good player will make serval trades to give every player a monopoly. By doing this, it gives everyone a shot at winning and makes the game much more fun for everyone. PLAY BY THE RULES and TRADE. If you play with someone that never trades it ruins the game. Don't play another game with someone that doesn't trade.

  36. …8 players? I thought the max was 6 for Monopoly.

  37. 2 Friends of mine and I have actually once played 3 games of Monopoly within one night, each one with a clear winner (I won once and my boy Mike won twice)

  38. I guess the Fines Paid To Free Parking, and the next person to land on it collects the kitty rule, was too complicated to code!

  39. A bit late but looks like a few of the endless games use more money then there is in a monopoly game, how many would end if money coming in was capped?

  40. I have never ended a monopoly game, the rules says you have to own all the properties from one color to buy a house or hotel, knowing this who is stupid enough to sell/trade properties, so you cant trade with others, if all the colors where the same price for houses and hotels, maybe trade could be an option (MAYBE, but one again, if other player owns a full color that will make things harder for you), you have to be SUPER LUCKY to fall into every space with the same color and the other playes do not fall into the free color you try to earn and you can't go bakrupt if you fall into other players properties without houses or hotels

  41. Question that comes up a lot:

    How does trading work in this simulation?
    Basically, each player has two lists: one of the things they want (missing pieces to complete a monopolly) and things they offer (stray one-of-a-color property). Every move proran search a match between pairs and trios of players – to match what they wish for and offer. If such a match found – property is excahnged, whoever gets the expensive one, pays the price difference to ehoever had a cheaper one.
    I agree it is quite basic – and it is a little unfair to whoever trades a cheaper item. But my question is: what it is like in real life? When you trade a 100 plot for 200 plot – what do people do in this situation?

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