Starting Money Cheat
Search in the directory C:\Program Files\Infogrames Interactive\Monopoly Tycoon\ or your custom install path for the initialpref.* file. This file is located in each scenario folder.
By opening the file in Notepad, you can edit the starting money amount for both yourself and your CPU opponents. Note: The same amount will be given to both you and your CPU opponents. Edit this in each scenario folder, and don't forget to make a backup in case you make a mistake.
Unlock Scenarios and Unlimited Money
Play the first game and build the following on Pacific Avenue before the second time period: a bar, a restaurant, a theater, a bakery, an apartment complex and a clothing store. Build them as tall as you can at medium quality. Once built, save and quit the game. When you start again, all scenarios should be unlocked, and your budget will be unlimited -- it will read 100,000,000 but will never go down.
Auction Cheat
Start an auction, and then immediately save the game once the auction screen comes up. Quit and reload the game. If you do this correctly, all computer players should pull out of the auction, and you can acquire the property cheaply.
Unrivaled Building
Using any character, complete all the scenarios. After the final sequence, a new scenario will open up allowing you to build a "Megapolitan." You will be given $200,000,000 to build it and will have no opponents, leaving you free to build the city of your dreams.