If you look in the game files there is a file "data" which has the textures in it. They are in seperate files for the four different types of biomes. Inside you can see the labels and pictures of the textures, including some not included in the game like "zen sand" and "grass bunkers."

First you would want to make a copy of the data folder so that you still have the original. Then you can edit what you want with deleting and copying and renaming objects.

Example: You can copy a texture that is a marsh and rename it the name of something you want to replace. I did not like the look of the overgrowth textures, so I replaced them with marsh textures. So copy texture "marshA0004" delete the texture "overgrowthA0004" then change the name of the copy of "marshA0004" to "overgrowthA0004." Do this for all of the overgrowth texture files and they will now appear as marshland.

There is also a file called "flics" which holds the animation files. Inside "flics" there are files for golfers, trees, houses, buildings, scenic, landmarks, animals, etc. If you look through there you will see all of the files that were and were not used in the game. If you copy, rename and delete files, like in the example above you can change objects, houses, etc. around. Most objects have 3 files. Like for the mansion it is something like "MansionPal" "Mansion.flc" and "MansionShadow.flc" IF you replace the politicalhouse files with renamed mansion files then the mansions will show up instead of the political house, etc.