Just before Easter, it was revealed that Halo: Campaign Evolved had already been rated by the Korea Game Rating and Administration Committee (GRAC). This is typically something that happens only a few months before launch, and as we've previously reported, rumours suggest the game will be released during the Xbox Games Showcase on June 7.
Now we have another possible launch date, after a Korean retailer stated that Halo: Campaign Evolved is set to debut on July 28. That's a Tuesday, which is a common day of the week for Microsoft game releases. When this was noticed, the date disappeared quickly, but alert Reddit users managed to save screenshots as proof.
Meanwhile, data miners have found other evidence that actually supports July 28 as the premiere date after two dates were discovered: July 23 and July 28. Microsoft often releases more exclusive editions that let us get an early start five days earlier, and it's very likely that's what this is about.
Dates can change, but barring any unforeseen circumstances, there is still enough evidence to make this a well-founded guess.