The UB version of Halo for the Mac is fantastic. I've been playing Halo PC since October 2004. I was hooked by the single player campaign at first. The story is well written and the ending is hidden behind a twist or two. After beating the game once, I've been playing the multiplayer ever since. This is where Halo really shines. The multiplayer community is STILL very large, after 5 years. The graphics look great on the early 2008 Mac Pro with 4GB of RAM, an 8800GT, and two WD Raptors. Also no bugs with Leopard even though it was originally designed with 10.2!