If you need a portable version, it is available on iOS (and realMyst is available on Android) and a demo is available for both. It is also available on DS and PSP but I wouldn't recommend those version as much. I've played the iOS version and touch controls offer a good recreation of the original. Though I would recommend it for replaying the game, not playing it the first time. Some of the immersion is lost on playing a device that can provide other distractions. For me, playing through while sitting down at a screen with a notebook next to you for tracking things you find, is the best way to play for the first time.
