The Omega Stone extends the adventure experienced in its predecessor,
[Riddle of the Sphinx][1], in which players were left with the
question, "Did Sir Geoffreys actually find the elusive Ark of the
Covenant?" The quest leads beyond Egypt to some of the world's most
famous locations. Search and explore Chichen Itza, Stonehenge, Easter
Island, and Bimini in the Devil's Triangle, all of which are
reproduced with pre-rendered graphics or still photographic images.
The adventure is played from first-person perspective, in [Myst][2]
style. The game features a point-and-click interface, atmospheric
effects (rain, wind, etc.), cutscenes with live actors and in-game
animations, and many mysterious puzzles to solve. (MobyGames)

[Here][3] is a review.

Hybrid Mac/PC discs but both partitions contain the same (Mac) files

Compatibility
Architecture: PPC

G3 600 MHz processor
Mac OS X 10.2.6 or better
128 MB RAM (256 MB recommended)
12x CD-ROM drive
Nvidia GeForce or ATI Radeon 7500 video card or better
1 GB of free hard drive space

  [1]: http://macintoshgarden.org/games/riddle-of-the-sphinx
  [2]: http://macintoshgarden.org/games/myst
  [3]: http://www.uhs-hints.com/articles/reviews/tos.php