I can't add much to the positive reviews so far except for one comment. Apotheosis X loads incredibly fast on my iMac. This is in stark contrast to any other Marathon scenario I have ever played. It takes less than 10 seconds from the initial click to actually playing the game. That is amazing. Many other scenarios take upwards of 4 to 5 minutes to load and then when you quit playing, it takes another 4 - 5 minutes for the game to actually shutdown.
The gameplay is fast and smooth. The weapon systems feel right and are fun to use. I love how different the weapons are from previously published scenarios and how well they function in the game. I found myself using the pistol many times as it is actually very useful in this scenario. I really like the rocket launcher and main assault rifle with grenade launcher -- they felt different from other scenarios and yet were fun, functional, and felt right in game play.
The enemies are done well. They are far more interesting in how they react and fight you than in most scenarios I have played. There were enough differences to make them interesting and deadly if you did not take them as a serious threat.
This is truly an outstanding scenario to play. Definitely one of the best if not the best. I loved the map layouts, complexity, and sizes -- very interesting how the architecture always felt right for the sci-fi setting and I enjoyed the soundtrack playing in the background. I can't say enough good things about this scenario. Simply amazing to play.