RollerCoaster Tycoon is arguably one of the finest simulations to date. The premise is simple: you're the manager of a theme park and you have plenty of money and technology at your disposal to turn the barren strip of land into the most fun place on earth.
This 1999 hit received two sequels—one of which was less than stellar—but none of them compare to the Deluxe version of the original game, which has since gotten a fantastic re-release on GOG.com to run on Windows 7, Vista and XP computers.
Additionally, the game includes both the Corkscrew Follies and Loopy Landscapes expansion packs.
Pick it up here.