Back when the Macintosh meant a machine with a built-in black & white screen, there were some extremely popular games -- but for the generation that remembers the introduction of the Mac II's color display, the unmistakable gameplay of Crystal Quest is sure to spark a deep sense of joy. Collecting those crystals and escaping through the hyperspace hatch caused your Mac to emit a sigh of... well, relief would be the polite way to put it (I'm trying to find a sample of the audio to link). Xbox 360 owners have had a Crystal Quest version for a couple years now, and Vista users also got a build to play with.
The wild crystal excitement has made its way back to the future, as an iPhone/touch version of Crystal Quest is available. While it lacks the level-finishing 'ahh!' of the original, the rest of the gameplay should be familiar to graying fans of Mac OS 6-vintage entertainment. Crystal Quest is $4.99 in the App Store.