Missed this but Deadline reported that the Halo series is at 81m copies sold.
Last reported number was on July 13th, 2015 for 65m.
Zhuge reported 70m sold on June 9th, 2016, adding the reported 5m Halo 5 copies sold to the 65m number.
So since June 2016 - February 2021 it has sold 11 million extra, likely split mainly between continued Halo 5 sales (beyond 5m), Halo MCC sales + Steam release and Halo Wars 2.
Well, since the Zhuge 2016 number 70m numbers, 3 Halo games have released, Halo Wars Definitive Edition, Halo Wars 2, and Halo MCC for PC, plus we would have had continued legs for mainly Halo 5 and MCC for Xbox One (Halo 4 and older Halo games wouldn't be selling much by that point).
Michael Pachter claimed in 2017, a year after the last official Halo 5 five million+ number, that he was told by somebody at MS that Halo 5 lifetime sales were trending towards the bestselling games in the Halo series, so most likely 8m+ by that point. So, I'm going to guess the breakdown of those 11m sales from 2017 to now is something like this:
- Halo 5- 4.5m sales (9.5m+ life to date)
- Halo MCC- 4m sales, including roughly 3m on Steam and roughly 1m on continued Xbox One legs (life to date of roughly 9m+)
- Halo Wars 2- 2m sales
- Halo Wars Definitive Edition- 500k sales (it's in the 200k-500k range on Steam Spy, plus it released on Xbox, so roughly 500k combined is likely a safe bet)