Bungie have said that ideas for Halo on the DS were pitched several times...

In a recent interview with Siliconera, Bungie have said that ideas for Halo on the DS had gone round.

When asked if Halo DS ever existed, Bungie's Brian Gerard replied "Every once in awhile it comes up. Somebody out there some developer pitches and tries to make it happen." He then went on to say that it was likely that a developer had made a prototype before trying to pitch it. Other than that, Halo never existed on the DS.

When asked if Halo DS would be possible, Bungie mentioned that the DS "he problem is the DS is not an FPS console right? It's not an FPS handheld." (perhaps Metroid Prime Hunters and Call of Duty 4 will convince them otherwise?), and suggested that a sidescroller would be a better option, if the project was ever started.