Just when I thought there wasn't a better game out there than 'The Sims', 'Roller Coaster Tycoon' gives that game a run for its money.  This game is so fun!  You don't just get to build roller coasters, you can build log rides, water slides, and a variety of other pre-made carnival rides: carousels, ferris wheels, etc.  Add paths, scenery, and shops and you have the park of your dreams!  It's so rewarding to watch the little people clamor to get in line for your rides, and to see them jump up and down with glee if they enjoyed the ride.  If they're hungry, build them a popcorn stand.  If they're tired, build them some benches.  Though the game looks a little complicated and overwhelming at first, once you get the hang of it, you'll be fine.  The manual is pretty good and should help you along.  My only complaints are the sound effects -- hearing the people squeal with glee is great, but hearing the toilets in the little bathrooms flush is not.  Whether you're a kid at heart who has always loved amusement parks, or a tycoon-in-training, you're bound to like this game.