There was another bug in the original Transport Tycoon (not Deluxe) that gave an even easier way to make massive amounts of money. If you built a tunnel through the whole continent the price integer rolled over and instead of paying a ton of money for the you actually received billions of dollars.
Oh yeah, the game was amazing in what it did with limited resources, but once you started pushing it, plenty of interesting bugs surfaced.
Another fun one was trains drive 1 pixel of the rails before turning around. So if an opponent has a huge profit making railway station, you place one rail of your own at the end and stop a train just before it turns around. Next time his trains come around, he crashes into yours and boom goes the money maker.
And then there was the fact that a train cant collide with itself. If it is long enough you can push it through itself at a crossing.
I remember that I like bully the AI when is slowly building a railway or road. I think that I like to do, was putting a depot with a cheap train and a railway crossing his road. So I stop the train on the road and it become blocked. or make the train to collide the bus/truck...
What I used to do with the AI is when it starts running a bus route you can lead the buses into your own road, then cut it off. Then the buses will just drive around in a circle forever, constantly breaking down because they never get to the depot.
In my experience, large applications are amazing in what they fail to accomplish with nearly unlimited resources, and most of their bugs are boring ;-)
In this earlier post I described making a maze solving bot to quickly and automatically generate millions of Simoleons, and an ad-hoc solution to the delivery problem:
And the other problem was that TSO just wasn't designed to make it easy to transfer large amounts of Simoleons from player to player.
You couldn't just "wire" somebody an arbitrary amount of cash via in-game email -- you had to show up on their lot and meet them at a specific real time, and suspiciously hand it over to them $1000 at a time.
There was another better way to transfer cash more efficiently than handing it over grand by grand, and that was with tip jars: You could fill a tip jar with $5000 using the pie menu with a couple of mouse clicks, and then the user could empty it the same way.
So when I had to deliver our first million Simoleons, I came up with a system where I'd go to the lot of the customer and meet them, then ask them to line up a bunch of tip jars in a row. I would then use bot macros to fill each tip jar one by one with $5000, while the customer would quickly empty them as I filled them up, and then we'd go back to the beginning of the row and start all over again, until we'd transferred the entire million Simoleons, in only 200 $5000 hand=>jar=>hand transactions instead of 1000 $1000 hand=>hand transactions.
One time when we were making a big delivery of cash, running the gauntlet of tip jars in our customer's living room (which I admit looked pretty fishy), and their housemate came home, saw what was happening, and wisely sussed up the situation that there was some kind of deal going down, that she wanted in on.
So she put her own tip jar down at the end of her housemate's row of tip jars, and I blithely deposited $5000 into her tip jar several times, which she immediately snapped up.
When I realized what happened, instead of contracting The Sims Mafia [2] to do a hit on her, I congratulated her for her loose morals and ingenuity. It was such a great hack, and I totally fell for it, and had more Simoleons than I knew what to do with anyway. It's all about good customer service!
It was a fun experiment, but other bots and offshore farmers were starting to work the system too, and customer service and delivery problems made it not worth continuing.
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[2]
Schneier on Security: Virtual Mafia in Online Worlds
Indeed, I had friends who used it (I never did), from what I recall (this was over 20 years ago), the tunnel could not be removed and in some cases would get in the way of some construction later.