Halo DS (lost Nintendo DS tech demo; 2007)
Halo DS was an unsolicited demo of a game in the Halo franchise for the Nintendo DS.
The first mention of this game was on January 4th, 2007, when IGN's Matt Casamassina made a blog post claiming to have played Halo DS. He claimed that the game was "completely up and running and fully playable," although never released. On July 18th of that same year, in an interview with Siliconera, Bungie employees Frank O'Connor and Brian Jarrard said that "there has never been an officially funded or sanctioned development of any sort of DS Halo game," and that Casamassina was likely referring to an unsolicited prototype pitched to Nintendo. This statement from Bungie employees caused people to accuse Matt Casamassina and IGN of lying about the existence of the game, to which Casamassina replied on October 2nd with a follow-up blog post. He stated that the game was real and that it was "created by a real development studio with a very big publisher," as well as releasing screenshots and gameplay videos of the game. In one of the videos, Matt is seen playing the game alongside Mark Bozon, who states that it was created by a "Triple-A publisher." 
Some people have drawn similarities between the gameplay footage of Halo DS with that of the port of Goldeneye: Rogue Agent for the Nintendo DS. This has lead to speculation that the publisher of the demo was Electronic Arts and that the developer was n-Space, the developer for the DS port of the aforementioned Goldeneye game.
- Bungie: If Halo DS existed it wasn’t from us - Siliconera Retrieved 18 Jan '20
- Halo DS Nintendo DS Video - On-Camera Halo DS Demo - IGN Retrieved 18 Jan '20