343 Industries has confirmed that the May 29th release date given by the Xbox Store for the Halo 3: ODST campaign in Halo: The Master Chief Collection was merely "a placeholder."
Releasing a statement on Twitter, the developer confirmed it was "inadvertently listed" on the Xbox Store, and that they are continuing "final testing." An official announcement will be given once a solid release date is determined.
A placeholder release date for the ODST campaign for Halo: The Master Chief Collection was inadvertently listed on the Xbox Store. (1/2)
— Halo (@Halo) May 27, 2015
We continue final testing and will make an official announcement once our release date is determined, and apologize for any confusion. (2/2)
— Halo (@Halo) May 27, 2015
Although the page has been removed, the fact that the date aligned with the May launch window 343 Industries gave earlier this month and back in April made sense.
In addition to ODST, 343 Industries also promised a remake of Halo 2's Relic map, completely reimagined for The Master Chief Collection. In Halo 2: Anniversary it will be officially known as "Remnant." While there was no mention of the Relic map's release, 343 Industries did previously say it would be included with this month's content update alongside the ODST campaign.
The free content is an apology to fans for the problems that plagued The Master Chief Collection's multiplayer gameplay at launch. Anyone who played the game between launch day and December 19, 2014, are slated to receive it for free.
The now-removed page also revealed a 8.1 file size for the ODST campaign, but there was no mention of other details, like a price for those who won't be getting it for free because they didn't play The Master Chief Collection during the qualifying period.