Steam

Steam is a digital distribution platform developed by Valve.

Halo Spartan Assault
On 4th April 2014 Halo: Spartan Assault was released on Steam, marking it as the first Halo game to arrive on Valve's digital distribution platform.

Halo Spartan Strike
Halo: Spartan Strike was the second Halo game to launch on Steam released on April 16th 2016 along side all other platforms.

Halo Wars: Definitive Edition
Halo Wars: Definitive Edition is the third Halo game to release on Steam, releasing on the 20th of April 2017. As well as being the first and only Halo game to use Valve's own Steamworks servers compared to Xbox Live. This however meant that players on the Steam version are unable to play with users on the Microsoft Store.

Halo: The Master Chief Collection
On December 3rd, 2019, 343 Industries launched The Master Chief Collection on Windows 10. The game is available through either Steam or the Microsoft Store that comes standard on all Windows 10 personal computers.

At launch, only Halo: Reach is available with plans for the other games to be released in chronological lore order. However, no dates have been provided for the next release (Halo: Combat Evolved Anniversary). However an Insider flight has been slated for January 2020.

The current release schedule is as follows:

Halo: Reach: December 3, 2019 Halo: Combat Evolved Anniversary: Sometime in 2020 Halo 2: Anniversary: Sometime in 2020 Halo 3: Sometime in 2020 Halo 3: ODST: Sometime in 2020 Halo 4: Sometime in 2020