Bungie used to make games for macOS. The predecessor Marathon Trilogy was originally released on macOS (and only Marathon 2 was ported to Windows). Halo was supposed to be originally released on macOS too, and then Microsoft bought the studio and turned it into an Xbox game, leaving all of the existing macOS userbase out in the cold.
Their purchase of Bungie also screwed up the IP rights to Oni. Wikipedia says that when Microsoft acquired Bungie, negotiations with Take-Two Interactive (which owned a share of Bungie) left Take-Two with the rights to Oni, and the sequel was eventually canceled. I don't have a citation on this but from what I understand, nobody is willing to touch Oni again (not even for an HD remake) because something about the IP rights is so messy that nobody wants to (or maybe nobody is even able to) untangle it. Which really sucks because it was a great game.
Right yeah, that's my mistake; it was showcased for release on both OSX and Windows at a MacWorld conference in the late 90s; Microsoft purchased Bungie in like 2000, and after that acquisition they added on an Xbox release.
Halo was an xbox exclusive for ages. I mean, not even available on Windows. They eventually released it for other platforms but it was years after and it felt dated and boring already.
