More expensive entertainment, but better quality.

    I personally like:

RollerCoaster Tycoon (2): Lots of fun and you can progress each time, you won't have to start over. Get the expansion pack "Loopy Landscapes/Corkscrew Follies" if you can.
SkiFree: A silly, simple game that comes free with some older Windows computers. There are ways to download it onto the newer computers, too.
The Sims: A great game, but has so many glitches that I don't play it much anymore.
Bugdom: An awesome game for Windows or Mac. Really cute, great graphics.
Alpha Centauri: My brother loves this futuristic game. A lot of options, so it's never exactly the same.
Jewel Chase: A fun puzzle game from the Microsoft Puzzle Collection. Since it's also a free game, it might be hard to get.
Mac Brickout: An awesome although old Mac game. You may be able to download it from the Web.