Was really surprised to see this run on an old MacPro, but it did beautifully. Only a few glitches, mostly with the tutorials. So, for those not sure if it will run, here are some specs that do run, and they run great here.
MacPro 2,1 2x 3.0GHz., 16GB ram, ATI 5770 (1GB) with 2x 24" screens.
The game is worth it, despite the trials and tribulations getting it to market.