Microsoft today announced Halo 2, the sequel to its most successful Xbox game to date. The game is not expected to be ported to the Mac or PC, however, and there is no mention of such in the announcement. Microsoft announced in July that it will be delivering Mac and PC versions of Halo in early 2003, making good on a promise that it would not discontinue those versions of the game following its acquisition of Bungie, the game’s developer.