What was all the fuss about, then?

It's still unclear exactly what all the events were leading up to the retraction of the announcement of Halo for MacOS and Windows and then the following reconfirmation of same. It's rumored that Apple CEO Steve Jobs had something to do with it, which is possible since Halo was first announced at MWNY 1999 by Jobs himself. It's likely he had some strong feelings about a game developer given so much attention at an Apple event subsequently being purchased by Microsoft and cancelling all Macintosh development.

In addition, on the same day that Seropian confirmed Halo for MacOS, former Bungie and Apple employee Peter Tamte announced a joint venture between Microsoft and Apple to bring all Microsoft's games to the MacOS, headed by himself. It's was not yet known what involvement, if any, Tamte or this new company would have in bringing Halo to the Macintosh.

It has since been announced that Tamte's company, Destineer, will publish Halo for the Macintosh under their Bold label, along with several other Microsoft titles.