https://news.microsoft.com/2007/10/04/global-entertainment-phenomenon-halo-3-records-more-than-300-million-in-first-week-sales-worldwide/
http://majornelson.com/2012/11/12/halo-4-makes-entertainment-history-with-more-than-220-million-in-global-sales-in-the-first-24-hours/
http://venturebeat.com/2010/10/28/halo-reach-sold-350m-in-16-days/
MS has been doing this PR for a while, last time I knew those games still sold well. No units for any of those PR statements