Breaking Monopoly
by Scott Hardie on March 20, 2016
My latest pastime has been seeing if I can rig a video game of Monopoly to give me infinite money. It turns out that I can, but it's incredibly tedious, far more so than I thought.
I like to play with the NES version, because it's just colorful and fun enough without being too sophisticated in its AI. I'm not going to link to the emulator version that I use, but I'm sure it's easy to find one of the many online if you want to try it. The best hidden feature in the game is the "hurry" mode that makes the computer skip over all of the animation that you do, which is the only sane way to play.
A typical four-player game (me versus three AI opponents) usually nets me around $8000-9000 in assets and cash at the end. Since the computer won't quit, I wondered if it was possible to force a game to go on long enough to earn $10k, $20k, $100k, or maybe even a million.
First I had to beat the computer normally. This isn't hard in NES Monopoly. The AI opponent overvalues monopolies and undervalues cash. You can usually convince it to give up all of its cash and all of its other deeds (or close to all) in exchange for the final property that it needs to form a monopoly. Using those other newly acquired deeds, you can make similar deals with the other two opponents. This usually nets you a whopping amount of cash (several thousand dollars to their $0 apiece). It might even net you a monopoly of your own if the AI was that desperate to get one, but if not, you win every subsequent deed auction for peanuts, and you will soon have your own monopoly and all of the cash in the game. You build hotels, and a few minutes later, they lose.
That's normally game over, but I let the latest game go on. I eliminated two opponents and kept one alive deliberately. My plan was to keep giving it all of my cash and letting it lose the cash back to me in rent, all the while racking up more money with the cards and Go. It didn't work out as smoothly as I thought.
First of all, the AI is either too smart or too stupid, I can't tell which, to accept money for nothing. You literally can offer it $2000 for nothing and it rejects you. The only way to pull off such a lopsided "trade" is to sell it a property for $1 and then buy it back for $2000, which took me a while to figure out.
Second, the AI will keep holding on to its own properties, so it will keep pestering you for trades every couple of minutes, which becomes very annoying fast. Giving it only one property in a color group of three will shut it up. (It won't open negotiation asking for two properies, only one, and one is useless.) Eventually I just bought all of its properties for a few thousand each, just to transfer some cash to the AI's possession.
Then, there's the matter of balance. Putting hotels up everywhere will wipe out the AI's cash too quickly. Even just putting up a few is too fast. If you really want to maximize the cash that you're both getting, you have to demolish your houses and hotels and leave an empty board. (Obviously the AI cannot be allowed to keep a monopoly or it would defeat you with the rent.) It took me time to figure this out, but it worked: Basically, if you owned every property on the board with no houses or hotels, and the AI had thousands of dollars, the game would go on for a very long time. Both of you would keep passing Go and collecting the Chance and Community Chest cards, gradually racking up more and more cash. Eventually the computer would run out of money and the game would end, but this would take hours. Each time the computer's balance got too low, you could keep "give" it your money again, to make the process go on forever.
But the tedium involved! At this point in the infinite game, you just keep pressing A to roll the dice over and over, with nothing else happening. The game loses all interest whatsoever, because of course it would, and you stop paying attention. You can rig the A button to keep pressing automatically, but you can't truly look away or eventually the AI would run out of money and the game would suddenly end. You have to keep monitoring it yourself. That's an endless, terribly boring process.
So in the end, I did figure out how to rig the outcome that I wanted, but it turned out to be far less interesting than I thought it would be. Ninety minutes after the game started (most games last 10-15 minutes), I couldn't take it any more and built hotels all over the board. My opponent's $9000 didn't last long before it was back in my hands. The final tally for all of that effort? $19,770. A nice score, twice what I usually get, but I didn't even break $20k. Getting to a million would take a week of playing. Knowing that I can do it will have to be sufficient in lieu of proving it, because there's no way I'm doing this little experiment again.
Logical Operator
The creator of Funeratic, Scott Hardie, blogs about running this site, losing weight, and other passions including his wife Kelly, his friends, movies, gaming, and Florida. Read more »
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