Halo DS? IGN's Matt Casamassina has been going on about it for some time. Kept saying it was real, but showed no proof to back up his claims. Eventually, people just called fake over the whole thing.
The disbelievers are in for a big surprise, because Halo DS is actually real. When Matt found out that someone edited his Wikipedia page questioning his credibility on the matter, he decided that it was time to release screenshots and videos of the now-canceled Halo DS.
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Halo DS [IGN]