BitMob - Is Steam for Mac Really a Game-Changer?
Microsoft bought Bungie, and Halo was released as the flagship title for the Xbox in 2001 (a Mac port eventually surfaced in 2003). Feeling shafted, many Mac gamers blamed Bungie’s defection on a lack of support from Apple. The fact that other developers and publishers -- such as LucasArts and Valve --dropped their Mac development efforts around this time did nothing to dissuade them.

Apple has since lagged behind in driver updates and relevant graphics libraries, and, perhaps most tellingly, offered next-to-no advertising or marketing support to games on the Mac.