AI Learns Insane Monopoly Strategies

monopoly a game that is fun for all ages and is a staple of many people's childhoods this iconic game gave some people their best memories and their worst whether or not you look back on it fondly the question has probably crossed your mind what is the best way to win at monopoly let's break this game down and see what we can find the first thing you'll notice about monopoly is that it isn't chess you just aren't in control of everything your player does in fact when it comes to the movement of your piece you have next to no influence on where the player can end up which is determined solely by dice yes you can exert some control over when you leave jail but since you must make this decision before you roll the event is still randomized you cannot accept a dice roll there's only one way you can influence your positioning the chance that you roll a double goes up the longer you spend in jail this means that you are more likely to move to an even square the longer you stay it's not guaranteed but it's all you've got let's talk about probability monopoly is primarily a game of chance which means that even the perfect player won't win 100 of the time monopoly involves luck and the key to playing it better is understanding how to be more lucky the most efficient way to win at monopoly is to build properties on sets this increases the fine your opponents have to pay and in turn makes you more likely to win each set on the board has a different cost depending on how much money it makes back simply put the more expensive the cost the more expensive the fine this can make it unclear to which set is the best which if you want to play the game better is definitely something you should know to find out we're going to introduce spot number one it buys everything trades nothing likes to build houses and mortgages only when it needs to i placed four of these bots onto the board and made them play a million games this is what happened here are the win rates based on who went first second third or fourth you can see that players who go first have a slight advantage over players that go after them this isn't news to anyone what was surprising about this is how unfair monopoly becomes as the number of players decreases in a game of four players there is a five percent difference between the first and the last player in a game of three players this difference jumps to 18 and with two it's 57 that is a massive difference now it's important to note that these win rates only applied when the games had an outcome which as it turns out was not very often most of the games between these bots ended in a stalemate stalemates happened 70 of the time with four players they also happened 42 of the time with three players and four percent of the time with two this was mainly because none of them would trade that meant the only way they could win was to acquire a set purely by chance and if that didn't happen then none of them would ever inflict enough damage to bankrupt the others and the game would go on indefinitely interestingly when there was only one player in the game stalemates happened 100 of the time this is the main reason you should join my discord because even numbers show that life is more fun with others if we analyze the squares that the bots landed on the most it tells an interesting story we can clearly see that the most frequently visited place in the game is jail this is because there are many reasons you can end up there whether it be by card rolling three doubles landing on the go to jail tile or choosing just to remain there players often find themselves behind bars in fact the jail tile is so frequently landed on that the locations that proceeded land more players simply by being nearby another thing we can see is the falloff that occurs as we go further through the tiles the more turns you have the more likely you are to be teleported elsewhere jail is a big reason for this but the community chests and chance cards are also responsible for altering your journey this makes properties at the end of the board harder to reach except for mayfair of course or boardwalk or the rue de lepia or whatever you want to call it this also explains why the first few tiles in the game are so hard to get to since players need to go all the way around the board just to have a good chance of landing on them probabilities help show what sets are good but it's not conclusive evidence of which set is the best to figure that out we are going to introduce a new metric the relative win rate this metric will show us how likely the tile in question is to belong to the winner this will only include things that the player bought assets required from bankrupting others will not be taken into consideration here using this new metric we can finally determine which set was the best for these bots in first place we have the dark blues comfortably ahead of the others this is no surprise owning these properties is always a big advantage in second place we have the the browns the the browns some somehow the worst set on the board is now the second best set on the board this honestly perplexed me for the largest amount of time until i realized this in a game without trades getting a set is extremely difficult you have to get extremely lucky in order to acquire a set with three properties since this requires landing on all three without anyone else doing so this task is just far easier to accomplish with the sets of two so it makes sense as to why they both have such a high win rate let's back up a bit though if the brown set is the second best set on the board then you know you're not playing monopoly right and yeah we aren't trading anything without it the game is essentially a race to see you can get the first set if any with this in mind let's construct a new ai that learns how to play the game perfectly [Music] ah [Music] now i'm not going to pretend that i can just craft the perfect monopoly ai manually but you might be wondering how it's even possible in the first place considering the amount of randomness going on knowing what strategy works better in this game is quite difficult comparing two ai with a single game is practically futile since even the best possible ai can lose a game badly to a terrible one through bad luck just because 100 as one on a slot machine doesn't mean that the best strategy is to keep playing it is for this reason that the good strategies must be recognized by playing a large number of games this should allow for a fair comparison of players but it still doesn't answer how we are going to create our new trading ai to solve this we are going to introduce an algorithm called neat which stands for neuroevolution of augmenting topologies this algorithm combines neural networks with basic evolutionary principles neural networks are a recreation of the same mechanisms that allow our brains to think which when combined with evolution produces some amazing results need learners to accomplish things quickly like solving an xor gate or balancing a pole or solving an xor gate while balancing a pole there are almost endless possibilities this ability also extends to gaining a deep understanding of complex games which in this case will be monopoly in order for this to work the networks need to know what's happening on the board neural networks process data using neurons which receive sets of information they then combine this information and pass it on to their neighbors information comes into the network from the input neurons and passes out of it via the output neurons this is where we come in for monopoly we need an input for every piece of information on the board and an output for all the different actions we can take which as it turns out is quite a large set three input neurons are required for each player one for position one for money and one for get out of jail free cards for a total of 12 inputs there are 28 properties on the board each requiring two inputs one to represent the owner and one to determine if it's mortgaged additionally 22 of these properties can be built on so they all need an additional input to represent housing we also require one extra input for each property so that we can let the network know context for example do you want to buy the browns together all these input neurons now represent the board entirely for our outputs there are eight different decisions our monopoly ai has to make this includes buying mortgaging trading unmortgaging bidding building houses selling them and deciding what to do in jail a neuron will be created for each one of these altogether these neurons now form an interface that can play monopoly now we are almost ready to crunch the numbers just one more problem neat works by generating a population of agents that compete against each other during each generation each agent is ranked using a fitness value which rates how good it is at the given task fitness values dictate how the next generation of agents is made with higher scores being rewarded with more offspring the scores are typically marked like an exam where each agent attempts the same thing individually but this can't work for monopoly because after all it's a multiplayer game so agents need to compete against each other to account for this fitness values will be assigned by using a knockout tournament scheme agents will be randomly assigned to a group of four and forced to play several thousand games in that group once the games conclude the play with the most wins advances to the next round fitness will be determined by how far an agent gets in the tournament with one small exception after the first tournament concludes fitness will be determined by the tournament ranking but relative to where the previous champion goes who will compete again so if an agent is able to get further than the former champion it receives a higher fitness value this way new champions should always improve on their predecessors finally we are able to run the algorithm speaking of which let's run it all tallied up the ai played 11.2 million games against itself to reach this point which if it was a human would have taken about 1600 years at this point it's basically the golden monopoly so the only question to answer now is how did god learn monopoly the first thing that ai learned was that paying for jail is bad and favored cards and rolling dice that was a great idea said the ai you know what else is a good idea bidding three thousand dollars on every property and so it did just that and lost horribly most of the time after that it soon discovered building houses and unmortgaging and put them to good use as the ai progressed it began to start making more sensible decisions it was becoming aggressive when it was winning and passive when it was losing this is when weird things started to happen the ai then said you know what i figured it out and started mortgaging everything it owned without exception and that's it this strategy guaranteed a win every time monopoly has i'm just kidding this obviously doesn't work what happened instead is that every single game ended in a draw this however didn't last long you know what's better than altruism winning the ai paid off his insanely high debt to the bank and started winning again re-enabling his sophisticated strategies from before it also began to actively trade properties and well too i couldn't find a single trade that was uneven at this point the ai had progressed to the strength of an average human player and played like one too that's when the ai decided to pull its most spectacular trick out of the bag auction everything and bid next to nothing i have no words for this nevertheless its deep understanding of the game had become very apparent here is our final trading ai's favorite properties in all their glory we can see here that its love for the browns has evaporated and now the orange set stands as its favorite it also loves trains with the first strain being its favorite property in the entire game the red and purple sets are also well liked the ai also seems to really enjoy mayfair other than that we can see that the other properties are pretty equal in terms of preference and that's it two weeks of training to agree with human theory nice to know that we aren't that bad at games after all [Music] you

Channel: b2studios

Views: 2,250,614

Keywords: monopoly, monopoly strategy, strategies, ai, monopoly ai, monopoly bot, monopoly bot learns, bot learns monopoly, b2studios monopoly, b2studios ai, AI, monopoly AI, Monopoly AI, board game ai, b2studios board game ai, buy the browns, monopoly brown set op, brown set b2studios, NEAT, neuro evolution, monopoly NEAT, monopoly neat AI, youtube, awesome, cool, b2studios, B2 AI, browns best set, best set monopoly, how to play monopoly, play monopoly, monopoly gameplay, perfect monopoly

Id: dkvFcYBznPI

Length: 11min 29sec (689 seconds)

Published: Tue Dec 21 2021

Reddit Comments

[u/feral_philosopher]

I didn't realize how much I hated monopoly until I tried playing it with my kids.

[u/BadgerBash]

So they stopped the training as soon as it confirmed their hypothesis? Why didn't they keep going, there could be a better strategy?

I can only guess that maybe it would only use the last strategy and would not change for many generations, but it's not mentioned.

[u/butsuon]

His "tournament method" of determining fitness kills of potential successful AIs, they just didn't succeed at as fast of a rate. This creates an issue where you end up with large portions of the decision tree unmapped.

[u/cyniclawl]

"It's strategy was simple. Bid $3000 on everything" I'm dying

[u/eqleriq]

The UK board always had brown cheap properties, about 15 years ago they standardized US/Germany because every other board was brown.

The gripe I have with this video is the most missing information from the video, which will confuse people who don't play the game with the official rules... and that's the rule that if you land on a property and do not buy it, it goes up for auction.

He mentions this "auction everything and pay next to nothing."

But that's bullshit. There needs to be some calculation about how much debt it is worth to take on to stop someone from getting a monopoly on a property.

It's similar to a "dollar auction" problem except it has a cap on whatever the player's assets are and instead of losing how much you bid, you are risking a later monopoly by letting it go.

So this "which properties do the AI prefer" is meaningless without knowing how much they're willing to bid / risk on it and how frequently that risk pays off.

​

Crap video IMO

[u/Gunningham]

There’s brown ones?