Instructions
Open a Web browser and search the Mega Upload website for "Mattatt14Mattatt14's Space Mountain."
Download the package from the website. You may need to wait 45 seconds to be able to download the package for free.
Find the downloaded file on your computer and right click on the icon. Then choose "Extract to Desktop."
Open "My Computer" from the desktop, then "My Documents" and finally "Program Files." From here, double click on the Atari logo.
Open the "Roller Coaster Tycoon 3" file from the "Program Files" folder. Then, open "Style" and, finally "Themes."
Drag the Space Mountain file from the Desktop into the "Theme" folder.
Launch "Roller Coaster Tycoon 3." Space Mountain will now be available when you enter build mode.