A while ago I made a blog about cancelled games, yet was thinking of a game I wanted to include, couldn't remember. After a session of Halo, I remembered that the game I was thinking about was the little-known "Halo DS". Now you might be thinking "Megas, what the hell do you mean by Halo DS? Why the fuck would a Microsoft game be on a Nintendo console?" First off, it's rare(pun not intended) but Microsoft does put several games on Nintendo handhelds like the DS and the GBA, though mostly it's RARE IPs like Banjo Kazooie, Viva Pinata and Diddy Kong Racing (though even Blue Dragon got a release). It's most likely a combination of those IPs having audiences in the Nintendo handhelds, Microsoft not having any dedicated handhelds of their own, and didn't want to put them on the PSP. Halo could have also been one of those games, but unfortunately the idea never got passed it's pitched stage.

The original pitch involved the game running on a Goldeneye Rogue Agent mod in the Zanzibar level of Halo 2(confirmed by a Bungie employee). The game started out as a rumor when former IGN editor Matt Casamassina said he actually played the build, and later

As for why the game was never greenlit, no one knows exactly why except for the people involved, but many speculate that the parties involved, Bungie, Microsoft, and Nintendo. I mean, this involved putting Microsoft's flagship on the competition's platform(and it's not the case with RARE IPs, which were once Nintendo franchises), and would've involved lots of talks between the three. Ultimately, and unfortunately, the terms were never met, and the game was scrapped.

As for the game itself, while it would likely be a step down from the console games, it would probably the closest thing we'd get to getting Halo on the go.